Design and Development of Solid State Relay with ...

Design and Development of Solid State Relay with Smart Monitoring and Control for Solar DC Grids

A Thesis & Project Submitted to the Department of Electrical and Electronic Engineering in partial Fulfillment of the Requirement for the Degree of

Bachelor of Science in Electrical and Electronic Engineering (EEE)

Department of Electrical and Electronic Engineering United International University, Dhaka, Bangladesh

June 2017

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A Thesis on

Design and Development of Solid State Relay with Smart Monitoring and Control for solar DC Grids

By Name Tariqul Islam Md. Sajib Mia Ahmed Amirul Arefin Amitabh Halder

ID 021-131-085 021-131-086 021-131-088 021-131-097

Mail Address [email protected] [email protected] [email protected] [email protected]

Supervisor Mahmud Ibrahim ([email protected]) Senior Research Engineer Centre for Energy Research United Intentional University

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Dedication

To our Parents and faculties ………….

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Declaration It is hereby declared that this thesis or any part of it has not been submitted elsewhere for the award of any degree or diploma.

Signature of the Supervisor:

Mahmud Ibrahim

Signature of the Candidates:

Tariqul Islam

Md. Sajib Mia

Ahmed Amirul Arefin

Amitabh Halder

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Acknowledgements First and foremost, we would like to thank Allah, the Almighty. Secondly, we would like to thank our supervisor, Mahmud Ibrahim Senior Research Engineer, Center for Energy Research (CER), UIU, who found time to support and advice amidst his already filled up daily schedule. We further extend our heartfelt gratitude to our parents whose words of advice, care and support have brought here and whose love has kept us going.

Special thanks to all our friends, senior, junior brothers and sisters for their support, advice and encouragement.

Last but not least, our heart goes to Professor Md. Rezwan Khan, Vice-Chancellor of United International University (UIU) for his wise idea to do a unique job and making our dreams come true.

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Abstract Due to the rapid increase in demand for electricity, the solar dc grid system is essential for fulfilling the supply of electricity of the country. But in the DC grid system, there needs certain protection in transmission and distribution line from different kinds of significant electrical faults. That is why this project tried to figure out a proper solution to that problem. That is the simultaneous monitoring and control of solid state relay. This project is called smart system because if any overcurrent or overloading fault arises and if any unexpected interruption happens in the line of DC grid, then surely the certain connected load will trip and the data will send to a remote distance to proper monitoring and control it.

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Table of Contents Chapter 1: Worldwide Solar Energy Scenario 1.1Worldwide Solar Scenario............................................................................................................................ 11 1.1.1 Worldwide Solar Power Production and Consumption Scenario ............................................. 11 1.1.2 Amenities of Solar Energy Over The World .................................................................................. 14 1.2 Solar Energy Scenario in Bangladesh ...................................................................................................... 15 1.2.1 Different Types of Solar Grid in Bangladesh ................................................................................. 16 1.2.2 An Overview of Solar Grids ................................................................................................................ 18 1.2.3 Key Challenges of Solar PV Grid ...................................................................................................... 19 1.2.4 Solar Radiation in Bangladesh............................................................................................................ 20 1.2.5 Solar Power Projects in Bangladesh ................................................................................................. 21 1.2.6 Solar Energy Initiatives in Bangladesh ............................................................................................ 23 1.3 Concept of this project ................................................................................................................................. 24 1.3.1 Project Target........................................................................................................................................... 24 1.4 Literature Review .......................................................................................................................................... 25 Chapter 2: Introduction of Wireless Sensor Modules 2.1 Wireless Communication ............................................................................................................................ 28 2.1.1 Importance of Wireless Communication ......................................................................................... 28 2.1.2 Applications of Wireless Communication ...................................................................................... 29 2.2 Introduction of Wireless Sensor Network(WSN)…………………………………………………………………………………… …………………………………………………………………………………………………... 29 2.2.1 Applications of Wireless Sensor Network ..................................................................................... 30 2.2.2 Characteristics of Wireless Sensor Network ................................................................................. 32 2.2.3 Wireless Sensor Network Topologies ............................................................................................. 33 2.2.3.1 Mesh Networking ......................................................................................................................... 34 2.2.4 Components of a Wireless Sensor Node ............................................................................................. 37 2.2.4.1 End Nodes vs. Routers .................................................................................................................. 39 2.2.5 Hardware Constrains of WSN ........................................................................................................ 39 2.3 Contribution of wireless sensor module in this project ...................................................................... 41 Chapter 3: Project Description 3.1 Project Overview: .......................................................................................................................................... 43 3.2 Project Components ...................................................................................................................................... 44 3.2.1 Solid State Relay..................................................................................................................................... 44 3.2.2 Wireless Module (NRF24L01) ........................................................................................................... 52 3.2.3 Current Sensor (ACS712): ................................................................................................................... 54 7|Page

3.3Server.................................................................................................................................................................. 57 3.3.1 Examples of servers ............................................................................................................................... 58 3.3.2 Some major components of server .................................................................................................... 58 3.3.3 Advantages of using server ................................................................................................................... 61 3.3.4 Server implementation in this project ................................................................................................ 61 3.3.5 Principle of server in this project ........................................................................................................ 62 3.4 Overall Working Flow Diagram................................................................................................................ 63 Chapter 4: Project Outcome & Discussion 4.1 Current Sensor (ACS712) ........................................................................................................................... 65 4.2 Wireless Module (NRF24L01) .................................................................................................................. 67 4.3 Project Performance Evaluation ................................................................................................................ 68 4.4 Cost Analysis .................................................................................................................................................. 71 Chapter 5: Achievement and Motivation 5.1 Purposes and Architecture of DC grid system ...................................................................................... 73 5.2 Applications .................................................................................................................................................... 75 5.3 Future Scope.................................................................................................................................................... 75 5.4 Challenges ........................................................................................................................................................ 75 Conclusion .............................................................................................................................................................. 76 Refernces ................................................................................................................................................................. 77 Appendix ................................................................................................................................................................. 79 List of Figures Figure 1: Solar PV Capacity,2005-2015 ..................................................................................................... 11 Figure 2: Solar PV Capacity of Top 10 countries of the World,2015 ......................................................... 12 Figure 3: Top 10 countries based on added PV capacity in 2015 ............................................................... 13 Figure 4: Distribution of the SHSs (Solar Home System) in six divisions in Bangladesh ......................... 15 Figure 5: A 141KWp Solar mini grid Paratoli Islands of Raipura Upazila in Narsingdi district ............... 17 Figure 6: Average Solar Radiation over a year in Bangladesh ................................................................... 20 Figure 7: Wireless Sensor Topology ........................................................................................................... 34 Figure 8: Mesh Network Topology............................................................................................................. 34 Figure 9: Mesh Configuration #1 with Router Nodes and Gateway ........................................................... 35 Figure 10: Mesh Configuration #2 with Router Nodes and Gateway ......................................................... 35 Figure 11: Same Topology - Two Ways to Mesh (Inefficient vs. Efficient) .............................................. 36 Figure 12: Using Router Nodes to Extend Network Distance .................................................................... 37 Figure 13: Basic WSN System with End Nodes, Ethernet Gateway, and Host PC .................................... 38 Figure 14: The components of a sensor node. ............................................................................................ 40

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Figure 15: Solution for DC Grid Overcurrent Protection ........................................................................... 44 Figure 16: Conventional Relay ................................................................................................................... 45 Figure 17: DC input of Solid State Relay .................................................................................................. 46 Figure 18: Solid State Relay Output Circuit ............................................................................................... 47 Figure 19: Reed Relay SSR ........................................................................................................................ 48 Figure 20: Transformer coupled SSR ......................................................................................................... 49 Figure 21: Photo coupled SSR .................................................................................................................... 49 Figure 22: Solid State Relay Block Diagram .............................................................................................. 50 Figure 23: SSR Working Flow Diagram..................................................................................................... 51 Figure 24: Wireless Module (NRF24L01) .................................................................................................. 52 Figure 25: NRF24L01 along with antenna ................................................................................................. 53 Figure 26: Tested Circuit of ACS712 ......................................................................................................... 54 Figure 27: Current Sensor Module............................................................................................................ 555 Figure 28: Simple pinout of ACS712 ......................................................................................................... 56 Figure 29: Real image of the current sensor ACS712................................................................................. 56 Figure 30: Images of Server ........................................................................................................................ 57 Figure 31: Real Server ................................................................................................................................ 59 Figure 32: Overall Working Flow Diagram of this project......................................................................... 63 Figure 33: Figure of Ip(A) Vs Vout(V) ...................................................................................................... 65 Figure 34: Typical ACS712 Die Temperature versus Continuous DC IP Current ..................................... 66 Figure 35: IDMT Behaviour Curve ............................................................................................................ 70 Figure 36: Data observing from the server side .......................................................................................... 70 Figure 37: Schematics Diagram of a DC grid System ................................................................................ 74

List of Tables Table-1.2.2: Solar Grid Capacity and Different Problems........................................................................ 18 Table 1.2.6(a): Solar Energy Initiatives supported by Infrastructure Development Company Limited ..................................................................................................................................................................... 23 Table 1.2.6(b): Solar Energy Inactivates supported by Sustainable & Renewable Development Authority ................................................................................................................................................................. 24 Table 4.1: ACS712 Sustainable Pulsed DC Primary Current Rates ...................................................... 66 Table 4.2(a): Data rate test on open air .......................................................................................................... 67 Table 4.2(b): Data rate test on closed air ....................................................................................................... 68 Table 4.3: Project Performance Evaluation................................................................................................... 68 Table 4.4: Cost Analysis Chart ......................................................................................................................... 71 9|Page

Chapter-1 Worldwide Solar Energy Scenario

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1.1 Worldwide Solar Scenario Nowadays the worldwide scenario of solar power is being changed very rapidly due to its many advantages. Not only that every country in the world is trying to produce more electrical power from the solar, different types of technology have become available and adopted by several countries all over the world.

1.1.1 Worldwide Solar Power Production and Consumption Scenario We have earlier said that in the recent time the rate of change of solar power production and consumption have become significant and momentous for every country as well as the world. If we throw light on some practical data of capacity of the solar from the year 2005 to 2015 than we can clearly see that the, capacity of the solar have been increased significantly all over the world.

Figure 1: Solar PV Capacity,2005-2015[1] From the Global Report,2015, if we see in the year 2005 where the capacity of the solar was only 5.1GW but in the year 2015 it was 227GW. So, we can clearly see that the rate of change of capacity of the solar have been increased and it’s also effect on our economic growth as well as all sector of an induvial country those have solar plant. [1]

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Now if we want to look some major countries capacity over the solar plant than we can see that the most capable country is China by their 30% capacity after that we will find Japan those have 22%.

Figure 2: Solar PV Capacity of Top 10 countries of the World,2015 If we look at other countries like, USA, UK, India, Germany, Australia etc. their solar capacity would be 15%,7%,4%,3.3% &2% respectively. For instance, we can say that at the grace of time and also the significant development of the solar technology the production and the consumption rate of solar power have been increased rapidly. It is also very important to note that now a days many countries are taking some big steps and initiatives over solar plant because they want to increase their production rate in very short time, so it’s very much possible that after some year the rate of solar power capacity would even higher than now. If we see the extension of solar power capacity up to 2015 than we can clearly see that the growth of the solar power of some countries was very well over this time.

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Figure 3: Top 10 countries based on added PV capacity in 2015 So, if we want to illustrate the Fig:3, we can say that the extension of the solar capacity till 2015 China was still dominating by their 15,150 MW generation after that Japan, USA, UK were also in very good extension solar power by their capacity of 11,000MW, 7,300MW,3510MW respectively. South Asia region India has done great deal of work for extension of solar power. In the western European countries, the rate of extension the solar power Germany was really good which 1450MW was. The representative of both country and continent the generation of solar power in Australia was 935MW. South Korea, France and Canada have also very well generation rate. [1] The rapid growth of the generation of solar power really very optimistic over the world. Each country over the world is trying to generate more and more solar power. For that reason, each and every country economical & financial growth moving very vastly. It’s also important that it’s creating more occupation for every eco-friendly country as well as the world It’s also our duty to know the alternatives technology or method of the solar power and the alternatives of solar power would be hydro power, wind energy, biomass, wave energy and geothermal etc. Those alternatives have different types of technology and theory.

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1.1.2 Amenities of Solar Energy Over The World The generation of solar power increasing day by day because there are lot of advantages for that reason almost every country trying to adopt this echo friendly technology. So now we would present the major advantages of the solar plant.

1. Renewable Energy Source Solar energy is a truly renewable energy source. It can be harnessed in all areas of the world and is available every day. We cannot run out of solar energy, unlike some of the other sources of energy. Solar energy will be accessible as long as we have the sun, therefore sunlight will be available to us for at least 5 billion years, when according to scientists the sun is going to die. 2. Reduces Electricity Bills Since you will be meeting some of your energy needs with the electricity your solar system has generated, your energy bills will drop. How much you save on your bill will be dependent on the size of the solar system and your electricity or heat usage. Moreover, not only will you be saving on the electricity bill, but if you generate more electricity than you use, the surplus will be exported back to the grid 3. Diverse Applications Solar energy can be used for diverse purposes. You can generate electricity (photovoltaics) or heat (solar thermal). Solar energy can be used to produce electricity in areas without access to the energy grid, to distill water in regions with limited clean water supplies and to power satellites in space.[4] 4. Low Maintenance Costs Solar energy systems generally don’t require a lot of maintenance. You only need to keep them relatively clean, so cleaning them a couple of times per year will do the job. Most reliable solar panel manufacturers give 20-25 years’ warranty. Also, as there are no moving parts, there is no wear and tear. 5. Technology Development Technology in the solar power industry is constantly advancing and improvements will intensify in the future. Innovations in quantum physics and nanotechnology can potentially increase the effectiveness of solar panels and double, or even triple, the electrical input of the solar power systems. 14 | P a g e

1.2 Solar Energy Scenario in Bangladesh The scenario of solar energy in Bangladesh have been changed momentously in recent time due to the development of the solar technology, less cost and very high efficiency. At the rural side of Bangladesh and where electricity has not come so far due to very high cost of power transmission line, those types of region have been greatly emphasized for the solar energy. Not only that which places are very much warm due its sun heat those types of places selected for the solar plant in Bangladesh. The government of Bangladesh is very optimistic about the solar technology and they are planning to give much more emphasize on solar plant in near future. It’s also very significant thing that for producing solar energy Bangladesh is not only depending on the government because now in Bangladesh there are lots of private solar company those are greatly contributing. [5] For instance, it’s very important to see some statistical information which is related to solar energy in Bangladesh. With an estimated 40% of the population in Bangladesh having no access to electricity, the government introduced a scheme known as solar home systems (SHS) to provide electricity to households with no grid access. The program reached 3 million households as of late 2014 and, with more than 50,000 systems being added per month since 2009, the World Bank has called it "the fastest growing solar home system program in the world. “The Bangladeshi government is working towards universal electricity access by 2021 with the SHS program projected to cover 6 million households by 2017. Here we try to present an overview of solar home system in Bangladesh.

Figure 4: Distribution of the SHSs (Solar Home System) in six divisions in Bangladesh

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1.2.1 Different Types of Solar Grid in Bangladesh We will discuss here about, (a) Solar Mini Grid, (b) Solar Micro Grid ,(c) Solar Nano Grid. At the beginning, we would like to describe about the (a)solar mini grid. First of all a solar mini grid is defined as a solar PV plant with a localized distribution network to a single village, or a. cluster of villages, providing alternating current (AC). First solar mini grid implemented in Chittagong, Sandwip which was a 100KW mini grid. In recent time, A 141 KWp Solar mini grid established by Souro Bangla Ltd has inaugurated its mini-grid solar power plant at Paratoli Islands of Raipura Upazila in Narsingdi district. [6]

The great advantages of solar mini grid is it improved the overall quality also lower investment for compact villages, the energy saving can be practiced using improved management tools. It has also very lower maintenance costs.

In general, A (b) solar microgrid is smaller than a mini grid and provides direct current (DC). So, solar micro grid basically connected to both the local generating units and the utility grid thus preventing power outages. Excess power can be sold to the utility grid. Therefore, it is a smallscale power grid that can operate independently or in conjunction with the areas main electrical grid. There are several types of micro grid such as, off grid micro-grid, campus micro-grid, community micro-grid. A micro-grid generally operates while connected to the grid importantly, it can break off an operate on its own using local energy generation in times of crisis like storms or other reasons.

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Figure 5: A 141KWp Solar mini grid Paratoli Islands of Raipura Upazila in Narsingdi district Now we will put throw light on the (c) Solar Nano grid, which provide clean, reliable and affordable electricity to small off-grid communities. The great advantage of solar Nano grid over other (usually household-focused) programs is that they don’t solely focus on the individual, but also bring additional collective community benefits. Our research and development has introduced additional collective community benefits, not available from other programs, including the establishment of village energy committees, and the implementation of training programs for the better management of the systems over their lifetime. Solar Nano grid is very much important due to our project is relate with it.[8] After getting some knowledge about different types of grid we will now see the most recent and popular solar technology which is (c) Solar Home System, for electrification of rural area through solar PV technology is becoming more popular, day by day in Bangladesh. Solar home system has become increasingly popular among users because they present an attractive alternative to conventional electricity such as no monthly bills, no fuel cost, very little repair, maintenance costs, easy to install anywhere etc. [7]

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1.2.2 An Overview of Solar Grids Table-1.2.2: Solar Grid Capacity and Different Problems Grid

Capacity

Mini Grid

50KW-1MW

Problems/Short Comings 1.Very much complex system. 2.Function depends on availability of the fuel for that reason noise & immersion create.

Micro Grid

5KW-50KW

1.Higher relative infrastructure cost. 2.Utilities of ownership could be prohibited in some areas.

Nano Grid

0.5KW-5KW

1. Range of the coverage area is small 2.Number of sharing communities are minimum

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1.2.3 Key Challenges of Solar PV Grid The major challenges of solar PV grid are as follow: 1. Cost The initial cost for purchasing a solar system is fairly high. Although the UK government has introduced some schemes for encouraging the adoption of renewable energy sources, for example the the Feed-in Tariff, you still have to cover the upfront costs. 2.Efficiency In order for photovoltaics to become a more mainstream and pragmatic energy source, the efficiency of solar panels will need to improve dramatically. Green, a world-renowned figure in photovoltaic research, was thoroughly optimistic about improving solar cell efficiency. Currently, modules vary between 13 and 20 percent efficiency, but, according to Green, the future could hold efficiencies of up to 40 percent. 3. Weather Dependent Although solar energy can still be collected during cloudy and rainy days, the efficiency of the solar system drops. Solar panels are dependent on sunlight to effectively gather solar energy. Therefore, a few cloudy, rainy days can have a noticeable effect on the energy system. You should also take into account that solar energy cannot be collected during the night.

4. Solar Energy Storage Is Expensive Solar energy has to be used right away, or it can be stored in large batteries. These batteries, used in off-the-grid solar systems, can be charged during the day so that the energy is used at night. This is good solution for using solar energy all day long but it is also quite expensive

5. Uses a Lot of Space The more electricity you want to produce, the more solar panels you will need, because you want to collect as much sunlight as possible. Solar panels require a lot of space and some roofs are not big enough to fit the number of solar panels that you would like to have.

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5. Associated with Pollution Although pollution related to solar energy systems is far less compared to other sources of energy, solar energy can be associated with pollution. Transportation and installation of solar systems have been associated with the emission of greenhouse gases. 1.2.4 Solar Radiation in Bangladesh The solar radiation varies season to season in Bangladesh for that reason we would never get same radiation over a year so it’s very important to know the significance & theory of the solar radiation. The greatest amount is available between two broad band’s encircling the earth between 15” degree and 35” degree latitude north and south.

Figure 6: Average Solar Radiation over a year in Bangladesh Fortunately, Bangladesh is situated between 20.43” degree north and 26.38” degree north latitude and as such Dhaka, the capital of Bangladesh, is located between latitude 23.6” degree and 23.9" degree North and longitude 90.5 degree and 90.8 degree east.[5]

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1.2.5 Solar Power Projects in Bangladesh The rapid growth of the solar power demand there are lot of project have already been completed, some projects are ongoing status and some will be come in the near future, Here we try to present some big initiatives steps by Bangladesh in the field of solar power.

Major Solar PV implemented by BPDB [2]

2011-12 1. 32.75 kWp at WAPDA Building, Motjheeel. 2. 2.82 kWp at Chairman Banglo, BPDB. 3. 6 kWp at Agrabad Bidyut Bhaban, Chittagong. 4. 1.8 kWp at Cox's BPDB Rest House. 2011-12 1. 37.5 kWp Solar Roof Top System on15th floor of Bidyut Bhaban. 2. 3 kWp at PC Pole Factory, Chittagong. 3. 3 kWp at Khagrachori BPDB Rest House. 4. 2.16 kWp at Swandip Power House and Rest House. 5. 2.16 kWp at Sales & Distribution Division, HatHajari. 6. 3.12 kWp at Sales & Distribution Division, Fouzdarhat. 7. 3.12 kWp at Sales & Distribution Division, Rangamati. 8. 1.6 kWp Solar Power System at Titas 50 MW Peaking Power Plant. 9. 1.6 kWp Solar Power System at t Baghabari 50 MW Peaking Power Plant. 10. 1.6 kWp Solar Power System at Bera 70 MW Peaking Power Plant. 11. 1.5 kWp Solar Power System at Chittagong Power Plant. 12. 3.5 kWp Solar Power System at Ghorashal Power Plant.

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2012-13 1. 4 kWp Solar Power System at Khulna Power Station. 2. 1.6 kWp Solar Power System at Faridpur 50 MW Peaking Power Plant. 3. 1.6 kWp Solar Power System at Goplagonj 100 MW Peaking Power Plant. 4. 2 kWp at Sales & Distribution Division, Bakolia. 5. 2 kWp at Sales & Distribution Division, Pathorghata and Madarbari. 6. 2 kWp at Sales & Distribution Division, Stadium. 7. 2 kWp at Sales & Distribution Division, Agrabad. 8. 2 kWp at Sales & Distribution Division, Halishohor. 9. 2 kWp at Sales & Distribution Division, Khulshi. 10. 2 kWp at Sales & Distribution Division, Pahartoli. 11.2 kWp at Sales & Distribution Division, Mohora. 12. 2 kWp at Distribution Division, Patiya. 13. 2 kWp at Distribution Division, Bandarban. 14. 6 kWp at Regional Civil Construction Division, Medical centre and Magistrate Building. 15. 2 kWp at Sales & Distribution Division, Feni. 16. 2 kWp at Sales & Distribution Division, Chowmuhuni, Noakhali. 17.1 kWp Solar Power System at the non-residential building and 2 kWp Solar Power System at the residential building of Santahar 50 MW Peaking Power Plant. 18. 1 kWp Solar Power System at the non-residential building and 2 kWp Solar Power System at the residential building of Katakhali 50 MW Peaking Power Plant. 19. 1.6 kWp Solar Power System at Dohazari 100 MW Peaking Power Plant. 20 27.2 kWp Solar Power System at Chandpur 150 MW Combined Cycle Power Plant. 21. 25 kWp Grid Tied Power System at Chittagong Power Station.

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Ongoing Projects 1. 650 KWp (400 kW load) Solar Mini Grid Power Plant at remote Haor area of Sullah upazila in Sunamgonj district under Climate Change Trust Fund (CCTF) on turnkey basis. 2. 8 MWp Grid Connected Solar PV Power Plant at Kaptai Hydro Power Station,at Rangamati on turnkey basis. 3. 3 MWp Grid Connected Solar PV Power Plant at Sharishabari, Jamalpur on IPP basis. 4. 30 MWp Solar Park Project adjacent to new Dhorola Bridge, Kurigram on IPP basis. 5. Solar Street Lighting Projects in seven (7) City Corporations of the country. 1.2.6 Solar Energy Initiatives in Bangladesh Today, Bangladesh has one of the most successful renewable energy programs in the world. It’s really momentous that now many private and NGO companies contributes to enhance the solar energy in Bangladesh and government also giving much emphasis on this echo friendly technology. Therefore, we have to know several initiatives which had taken past from the many solar companies and also which would take in the near future. Contribution of those companies are really great so far because they try to electrification off-grid in Bangladesh. Table 1.2.6(a): Solar Energy Initiatives supported by Infrastructure Development Company Limited Program

Target

Achievements as of December, 2014

Solar Home System

6 million systems by 2018

3,500,000

Solar Irrigation

1,550 solar agricultural pumps

124

by 2017 Solar Mini Grid

50 solar mini grids by 2017

4

Solar-Powered Telecom Base

As per demand

138

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Table 1.2.6(b): Solar Energy Inactivates supported by Sustainable & Renewable Development Authority Type

Number

Solar Home System

4115250

Solar Irrigation

441

Solar Drinking Water System

122

From the above those table we can clearly see, that the contribution and the major initiatives of many solar companies are very much promising and significant. There are lot of solar companies now in Bangladesh for that reason now off grid region in our country become electrified very rapidly. [13]

1.3 Concept of this project The basic concept of this project to develop an indemnify protection for the distribution side of the solar grid. So, in this project we generally deal with the over current of the solar grid & this overcurrent originally produce by many reason most common reason is for the unwanted overload at the distribution side.

1.3.1 Project Target The fundamental objective of this project is to develop a smart relay for the protection from the over current purposes of the solar grid and make sure the protection between the solar grid and distribution side. For that reason, we build a smart relay not only ensure the protection but also it takes continues current reading from the distribution side and send it to the server through a wireless module after a certain time & the status of the distribution side could be monitoring simultaneously from the server side. A significant part of this project is that we could get current reading & status from each single distribution line so we can easily be monitoring the status of the different distribution line from the server side and also can record all the data. So, for the

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enhancement of the solar power using and also ensure the solar protection system we build such kind of relay. Therefore, when we were developing this project were very concern and keep eyes on the cost of the project and also, we were very concern about the efficiency. 1.4 Literature Review 1.

“Application of Smart Grid Techniques for Effective Control in a Mini-Grid System” by Md. Rubayatur Rahim Bhuyian, Raqibul Mostafa, Md. Fayyaz Khan and Umama Zobayer proposes smart grid operating techniques for efficient management of a mini grid connecting RE sources to household loads in a rural environment. The smart grid system can be designed to detect abnormal operating conditions and provide the necessary corrective measures like grid system will be capable of detecting overvoltage and under-voltage condition of the source of the grid (protective relay can use as protection). This paper has addressed the efficient operation of mini-grid by implementing intelligent and autonomous control mechanisms that are used in a smart grid system. Several applications have been presented illustrating the communication and control mechanisms that support the implementation of smart grid concepts.

2. “A review of the potential benefits and risks of photovoltaic hybrid mini-grid systems” by James, Anna Bruce, Iain MacGrill present an overview of the major risks identified included incorrect system sizing due to load uncertainty, challenges related to community integration, equipment compability issues, inappropriate business models and risks associated with geographical isolation. Most frequently identified risks are include load uncertainty, lack of effective business models and have persisted over time, from 2001 to 2013. 3. “Technical Aspects of Mini-Grids for Rural Electrification” by P.J Boait makes an attempt to the electricity generation technologies which is relevant for mini grids are first presented, followed by technical aspects of the downstream side and here also highlights the importance of coordinated operation and management of such small systems to ensure the reliable supplies.

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4. “From SHS to Mini-Grid-Based Off-Grid Electrification: A Case Study of Bangladesh” by Prof. Subhes Bhattacharyya analysis the overall local level study of a village off-grid system in Bangladesh whether mini-grids offer a better solution than SHS and the techno economic analysis of the optimal off grid system of the architecture is presented suing HOMER software. 5. ”Smart mini grid: An innovative distributed generation based energy system” by Mukesh Gujar, Alkkhya Datta, Parimita Mohanty” present that the TERI(The Energy and Resources Institute) used a software platform for acquiring data, sending and receiving data controls. TERI made a research project at Hariaya, India on solar power with off grid facility where NI (Natural Instruments) helped by giving the instruments of communication named NI Compact-R10922(C-series). 6. “Off-grid electrification with solar home system: An appraisal of the quality components by Shahriar Ahmed Chowdhury, Monjur Mourshed they developed a technical quality of solar home system components like PV panel, battery, charge controller and lamp circuit or inverters in off-grid areas. Here, the components are inferior quality and there have some suggestion for improve this condition 7. “Solar-Diesel Hybrid Energy Model for Base Transceiver Station (BTS) of Mobile Phone Operators” by Shahriar Ahmed Chowdhury, Shakila Aziz looks at technical, economic and financial grounds for corporations to use renewable energy in place of fossil fuels. Without using a storage system, PV energy is cheaper than the diesel generator for small systems like BTS. Also price of diesel is highly variable and unpredictable where price of solar panel is continuously declining. 8. “Design and Implementation of a Low Cost Wireless Sensor Network using Arduino and nRF24L01(+)” by Zeeshan Ali, Abid Rahim and Syed Sabeel Nawaz presented that the world is growing and moving very vastly in respect to the time that is why they have developed using open-source hardware platform, Arduino. The system is low-cost and highly scalable both in terms of the type of sensors and the number of sensor nodes and in this paper, they gave overall system architecture and the design of hardware and software components.

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Chapter-2 Introduction of Wireless Sensor Modules

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2.1 Wireless Communication Wireless communication uses transferring or receiving different types of data and information. It is connected two or more devices without any types of electrical conductors. There has fixed channel to transfer data or information from sender to receiver. There have also frequency and bandwidth. There are different types of wireless communication device which we use for different purposes. Different types of wireless device are router, wireless adapters, wireless repeater, wireless phones, Bluetooth, NRF24L01. In this chapter, we would try to give focus on one of the significant device NRF24L01. [5]

2.1.1 Importance of Wireless Communication Wireless communication has several advantages with the following being some of the most important: •

Cost effectiveness - unlike communication that entails the use of connection wires, this type of communication does not require elaborate physical infrastructure or maintenance practices. This means any company providing wireless communication services does not incur a lot of costs, and as a result, it is able to charge cheaply with regard to customer fees

  •

Flexibility - wireless communication enables people to communicate regardless of their location. It is not necessary to be in an office or some telephone booth in order to pass and receive messages.

  •

Convenience - wireless communication devices like mobile phones are quite simple and therefore allow just about anyone to use them wherever they may be. There is no need to physically connect anything in order to receive or pass messages.

  •

Constant connectivity - whether someone is traveling or seated at the beach, he or she can still stay in touch with loved ones or important business contacts. Constant connectivity also ensures that people can respond to emergencies relatively quickly

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2.1.2 Applications of Wireless Communication

Now a day there are several applications of wireless communication over the universe and some of them are very known and very popular between us. One of the best-known examples of wireless technology is the mobile phone, also known as a cellular phone, with more than 4.6 billion mobile cellular subscriptions worldwide. One of the most significant application of wireless communication is Data communication. In data communication there are several technologies such as Wi-Fi, Cellular data service , Mobile satellite communications and Wireless sensor network Wireless data communications are generally used to span a distance beyond the capabilities of typical cabling in point-to-point communication or point-to-multipoint communication, to provide a backup communications link in case of normal network failure, to link portable or temporary workstations, to overcome situations where normal cabling is difficult or financially impractical, or to remotely connect mobile users or networks. Also, we can see for the energy transfer and also medical technology depends on the wireless technology.[5]

2.2 Introduction of Wireless Sensor Network (WSN) A wireless sensor network (WSN) is a wireless network consisting of spatially distributed autonomous devices using sensors to monitor physical or environmental conditions. A WSN system incorporates a gateway that provides wireless connectivity back to the wired world and distributed nodes (see Figure 1). The wireless protocol you select depends on your application requirements. Some of the available standards include 2.4 GHz radios based on either IEEE 802.15.4 or IEEE 802.11 (Wi-Fi) standards or proprietary radios, which are usually 900 MHz..

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2.2.1 Applications of Wireless Sensor Network

Area monitoring Area monitoring is a common application of WSNs. In area monitoring, the WSN is deployed over a region where some phenomenon is to be monitored. A military example is the use of sensors detect enemy intrusion; a civilian example is the geo-fencing of gas or oil pipelines. Health care monitoring The medical applications can be of two types: wearable and implanted. Wearable devices are used on the body surface of a human or just at close proximity of the user. The implantable medical devices are those that are inserted inside human body. Possible applications include body position measurement, location of persons, overall monitoring of ill patients in hospitals and at homes. Body-area networks can collect information about an individual's health, fitness, and energy expenditure. Environmental/Earth sensing There are many applications in monitoring environmental parameters, examples of which are given below. They share the extra challenges of harsh environments and reduced power supply. Air pollution monitoring Wireless sensor networks have been deployed in several cities (Stockholm, London, and Brisbane) to monitor the concentration of dangerous gases for citizens. These can take advantage of the ad hoc wireless links rather than wired installations, which also make them more mobile for testing readings in different areas. Forest fire detection A network of Sensor Nodes can be installed in a forest to detect when a fire has started. The nodes can be equipped with sensors to measure temperature, humidity and gases which are produced by fire in the trees or vegetation. The early detection is crucial for a successful action of the firefighters; thanks to Wireless Sensor Networks, the fire brigade will be able to know when a fire is started and how it is spreading.

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Landslide detection A landslide detection system makes use of a wireless sensor network to detect the slight movements of soil and changes in various parameters that may occur before or during a landslide. Through the data gathered it may be possible to know the impending occurrence of landslides long before it actually happens. Water quality monitoring Water quality monitoring involves analyzing water properties in dams, rivers, lakes and oceans, as well as underground water reserves. The use of many wireless distributed sensors enables the creation of a more accurate map of the water status, and allows the permanent deployment of monitoring stations in locations of difficult access, without the need of manual data retrieval.[8] Natural disaster prevention Wireless sensor networks can effectively act to prevent the consequences of natural disasters, like floods. Wireless nodes have successfully been deployed in rivers where changes of the water levels have to be monitored in real time. Machine health monitoring Wireless sensor networks have been developed for machinery condition-based maintenance (CBM) as they offer significant cost savings and enable new functionality. Wireless sensors can be placed in locations difficult or impossible to reach with a wired system, such as rotating machinery and untethered vehicles. Data center monitoring Due to the high density of servers racks in a data center, often cabling and IP addresses are an issue. To overcome that problem more and more racks are fitted out with wireless temperature sensors to monitor the intake and outtake temperatures of racks. As ASHRAE recommends up to 6 temperature sensors per rack, meshed wireless temperature technology gives an advantage compared to traditional cabled sensors. Data logging Wireless sensor networks are also used for the collection of data for monitoring of environmental information, this can be as simple as the monitoring of the temperature in a fridge to the level of 31 | P a g e

water in overflow tanks in nuclear power plants. The statistical information can then be used to show how systems have been working. The advantage of WSNs over conventional loggers is the "live" data feed that is possible. Water/waste water monitoring Monitoring the quality and level of water includes many activities such as checking the quality of underground or surface water and ensuring a country’s water infrastructure for the benefit of both human and animal. It may be used to protect the wastage of water. Structural health monitoring Wireless sensor networks can be used to monitor the condition of civil infrastructure and related geo-physical processes close to real time, and over long periods through data logging, using appropriately interfaced sensors.

2.2.2 Characteristics of Wireless Sensor Network The significant characteristics of wireless sensor network include: Power consumption constraints for nodes using batteries or energy harvesting Ability to cope with node failures (resilience) Some mobility of nodes (for highly mobile nodes see MWSNs) • 

Heterogeneity of nodes Scalability to large scale of deployment

•  •   

Ability to withstand harsh environmental conditions Ease of use Cross-layer design

Cross-layer is becoming an important studying area for wireless communications. In addition, the traditional layered approach presents three main problems:         32 | P a g e

1. Traditional layered approach cannot share different information among different layer ， which leads to each layer not having complete information. The traditional layered approach cannot guarantee the optimization of the entire network. 2. The traditional layered approach does not have the ability to adapt to the environmental change. 3. Because of the interference between the different users, access conflicts, fading, and the change of environment in the wireless sensor networks, traditional layered approach for wired networks is not applicable to wireless networks. So the cross-layer can be used to make the optimal modulation to improve the transmission performance, such as data rate, energy efficiency, QoS (Quality of Service), etc.. Sensor nodes can be imagined as small computers which are extremely basic in terms of their interfaces and their components. They usually consist of a processing unit with limited computational power and

limited

memory, sensors or MEMS (including

specific

conditioning

circuitry),

a communication device (usually radio transceivers or alternatively optical), and a power source usually intheformofabattery.

Other

possible

inclusions

are energy

harvesting modules,[14] secondary ASICs, and possibly secondary communication interface (e.g. RS-232 or USB). [4] The base stations are one or more components of the WSN with much more computational, energy and communication resources. They act as a gateway between sensor nodes and the end user as they typically forward data from the WSN on to a server. Other special components in routing based networks are routers, designed to compute, calculate and distribute the routing tables. 2.2.3 Wireless Sensor Network Topologies WSN nodes are typically organized in one of three types of network topologies. In a star topology, each node connects directly to a gateway. In a cluster tree network, each node connects to a node higher in the tree and then to the gateway, and data is routed from the lowest node on the tree to the gateway

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Figure 7: Wireless Sensor Topology Finally, to offer increased reliability, mesh networks feature nodes that can connect to multiple nodes in the system and pass data through the most reliable path available. This mesh link is often referred to as a router 2.2.3.1 Mesh Networking The gateways and nodes work together to form a mesh network. The gateway maintains a list of nodes (by serial number) that have been authorized for network access. When a node powers up, it scans for available networks, locates either a gateway or router, and attempts to join it. If the gateway has the node in its list, the node joins the network, downloads the latest configuration from the gateway, and begins its normal operation of acquiring measurement data and controlling DIO.

Figure 8: Mesh Network Topology Since each node joins a network instead of a particular router or gateway, it can find a new path back to the gateway in the event that the signal is lost or blocked to its existing network route. In 34 | P a g e

this way, the mesh network is inherently self-forming and self-healing. However, this may also cause network throughput to decrease, as there is no way to force a router or end node to join to a device in the network. Each time a node joins through a router, the overall throughput of that node is halved, since the node must hop to get its messages back to the gateway.[6]

Figure 9: Mesh Configuration #1 with Router Nodes and Gateway Figure 9, shows an example of one possible mesh configuration. In this configuration, R1 (a router) and R2 (a router) both communicate directly with the gateway. Measurements taken by both devices can directly reach the gateway without having to hop through another node. However, the configuration above does not always mesh in the same way. Figure 3 shows another possible configuration for the same network. [13]

Figure 10: Mesh Configuration #2 with Router Nodes and Gateway

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Figure 10, shows another possible configuration for the same network. In this configuration, R1 can still communicate with the gateway, but R2 is now connected through R1. This means that all measurements taken by R2 must hop through R1 before making it back to the gateway. In addition, R1 is now not only responsible for sending its own measurement data, but also the R2 data. This configuration is considered a worst case 1-hop system, as R2 and R1 both have the possibility of meshing through a router that is connected to the gateway. NI recommends configuring your system for no more than three hops. Configuring multiple nodes as routers and placing them within close proximity introduces the possibility that your system could mesh inefficiently. [13]

Figure 11: Same Topology - Two Ways to Mesh (Inefficient vs. Efficient)

This network can be improved with two separate techniques: 1. Convert some routers to end nodes. 2. Set up the network to prevent the routers from being in range of each other (spatially separated by distance, or introducing objects that increase radio interference such as buildings).[15]

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Figure 12: Using Router Nodes to Extend Network Distance Mesh network is the ability to extend the distance of the end measurement from the wired gateway. By placing mesh routers throughout the space where you wish to acquire signals, you can expand the area and distance across which measurement data can be acquired and sent. In an outdoor environment with line of sight, a single communication hop can extend up to 300m. NI recommends no more than three hops from any device to the gateway, meaning you can extend your measurements up to 900m from the gateway.

2.2.4 Components of a Wireless Sensor Node

A WSN node contains several technical components. These include the radio, battery, microcontroller, analog circuit, and sensor interface. When using WSN radio technology, you must make important trade-offs. In battery-powered systems, higher radio data rates and more frequent radio use consume more power. Often three years of battery life is a requirement, so many of the WSN systems today are based on ZigBee due to its low-power consumption. Because battery life and power management technology are constantly evolving and because of the available IEEE 802.11 bandwidth, Wi-Fi is an interesting technology. [17]

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Figure 13: Basic WSN System with End Nodes, Ethernet Gateway, and Host PC The second technology consideration for WSN systems is the battery. In addition to long life requirements, you must consider the size and weight of batteries as well as international standards for shipping batteries and battery availability. The low cost and wide availability of carbon zinc and alkaline batteries make them a common choice. To extend battery life, a WSN node periodically wakes up and transmits data by powering on the radio and then powering it back off to conserve energy. WSN radio technology must efficiently transmit a signal and allow the system to go back to sleep with minimal power use. This means the processor involved must also be able to wake, power up, and return to sleep mode efficiently. Microprocessor trends for WSNs include reducing power consumption while maintaining or increasing processor speed. Much like your radio choice, the power consumption and processing speed trade-off is a key concern when selecting a processor for WSNs. This makes the x86 architecture a difficult option for battery-powered devices. [16]

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2.2.4.1 End Nodes vs. Routers WSN measurement nodes can be configured to act as end nodes or routers using the Measurement & Automation Explorer (MAX) utility. In both configurations, the nodes can collect measurement data from sensors, control their DIO channels, or be programmed using LabVIEW WSN for more advanced capabilities. One trade-off to consider when configuring nodes is power consumption [15].To preserve battery power, an end node will reside in a lowpower sleep mode most of the time (depending on its user-defined sample interval), waking up only to sample and transmit data, along with other housekeeping information. A router node, however, is always awake and can relay data from other nodes back to the gateway. This allows you to extend distance and reliability in your wireless sensor network. Because they are always transmitting data, router nodes are designed to use external power at all times to send, receive, and buffer messages to and from end nodes.

2.2.5 Hardware Constrains of WSN A sensor node is made up of four basic components as shown in Fig. 14: a sensing unit, a processing unit, a transceiver unit and a power unit. They may also have application dependent additional components such as a location finding system, a power generator and a mobilizer. Sensing units are usually composed of two subunits: sensors and analog to digital converters (ADCs). The analog signals produced by the sensors based on the observed phenomenon are converted to digital signals by the ADC, and then fed into the processing unit. The processing unit, which is generally associated with a small storage unit, manages the procedures that make the sensor node collaborate with the other nodes to carry out the assigned sensing tasks. A transceiver unit connects the node to the network.

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Figure 14: The components of a sensor node. One of the most important components of a sensor node is the power unit. Power units may be supported by a power scavenging unit such as solar cells. There are also other subunits, which are application dependent. Most of the sensor network routing techniques and sensing tasks require the knowledge of location with high accuracy. Thus, it is common that a sensor node has a location finding system. A mobilizer may sometimes be needed to move sensor nodes when it is required to carry out the assigned tasks. All of these subunits may need to fit into a matchboxsized module [15]. The required size may be smaller than even a cubic centimeter [12] which is light enough to remain suspended in the air. Apart from the size, there are also some other stringent constraints for sensor nodes. These nodes must: • consume extremely low power, • operate in high volumetric densities, • have low production cost and be dispensable, • be autonomous and operate unattended, • be adaptive to the environment. Since the sensor nodes are often inaccessible, the lifetime of a sensor network depends on the lifetime of the power resources of the nodes. Power is also a scarce resource due to the size limitations. For instance, the total stored energy in a smart dust mote is on the order of 1 J . For wireless integrated network sensors (WINS), the total average system supply currents must be less than 30 lA to provide long operating life. WINS nodes are powered from typical lithium (Li) 40 | P a g e

coin cells (2.5 cm in diameter and 1 cm in thickness). It is possible to extend the lifetime of the sensor networks by energy scavenging, which means extracting energy from the environment. Solar cells are an example for the techniques used for energy scavenging. [18]

2.3 Contribution of wireless sensor module in this project In this project NRF24L01 is used for the sending data from the certain and induvial pole to the coordinator so the contribution of NRF24L01 is relay momentous in this project. NRF24L01 is connected with the Arduino Nano and getting continues reading of current and sending the related data to the coordinator after a certain time which probable one minute. For instance, if we see that the purpose of the NRF24L01 is mainly divided into two part, first if we look at the pole side we would see that the duty of the NRF24L01 is to send data to the coordinator and if we focus on the coordinator side than we would see that the duty of the NRF24L01 is to receive or decode data which is send from the pole after a certain time.

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Chapter-3 Project Description

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3.1 Project Overview: The project of smart relay design is implemented for safety of many problems in rural solar dc grid electrification. Though overloading problem is a big problem for this type of DC grid connection, in this project we tried to find its solution. The relay used in our project is combined with modern facilities like wireless communication and server implementation. Wireless communication is implemented by a wireless module device. Also in our microcontroller based smart relay, as a basic part, Arduino is used as microcontroller and a current sensor is used. Now-a-days Arduino platform is a common and available resource for using microcontroller. The whole system in this project works in sequences. If any overcurrent occurs from given current rate set on the relay in transmission line or load line which is measured by current sensor sends signal to the Arduino. Suppose current rate set at 3A, then any current flow over 3A the relay will be turned off but if current remains less than 3A then nothing happens to load and always in service. And it decides to open the circuit immediately for safety of load. The code in Arduino is given as if first two times fault occurs, the reconnect automatically but third times the circuit is totally disconnected. The data of current being checked in a time difference. And that data send to the coordinator of the system. For sending data, the wireless communication device used which is nRF24L01. Actually the system is divided in few zones as distributor side, and all data collected in the coordinator side from where the electricity supplied. Here, the coordinator works like monitoring device for the system where all data is accumulated. As a monitoring device or data stored device any type of single board computer can be used (e.g.: pcDuino). The system also has cloud connectivity. That means, if internet is connected then all data stored in the coordinator sends to cloud and from a long distance the authority can check the current condition of that DC grid. After that, they can take any decision by review these results of current condition. For sending data to the cloud, any type of 3g Wi-Fi modem can be used. So, one of these is used here which is advance addition. It has seen that cloud plays a very important role for this project. The flow diagram of the whole system is given later. Here, for the DC grid system, the overall review stands on this point that for any unavoidable condition of over current the current sensor senses this and send signal to the MCU. MCU checks the condition of current: if the current is less than 2A, the loads remain in connectivity and if the current is more than 2A, the SSR operate 43 | P a g e

and send signal to disconnect the load. The data of all these operating situations send to coordinator for further actions. The coordinator stores all data in one place. At last, all of these data is send to server using cloud.

Figure 15: Solution for DC Grid Overcurrent Protection 3.2 Project Components

3.2.1 Solid State Relay Electromechanical relay have been a primary method of switching for many years . It has a moving part. For some problems and limitation of electromechanical relay, solid state relay (SSR) offer possible solution to many of the EMRs disadvantage. solid state relay are not very different in general operation from mechanical relays that have movable contacts. SSR is an electronic switching device that switches on-off when small amount of voltage applied to its controlled terminal. SSRs made of semiconductor switching elements, such as thyristor, triacs, diodes, and transistor. Furthermore, SSRs employ optical semiconductor device called Photocouplers to isolate input and output signals. Photo couplers change electrical signals into optical signal and transmit the 44 | P a g e

signals through space, that fully isolating the input and output sections while transmitting the signals at high speed. [18] An SSR based on a single MOSFET, or multiple MOSFETs in a paralleled array, can work well for DC loads. MOSFETs have an inherent substrate diode that conducts in the reverse direction, so a single MOSFET cannot block current in both directions. For AC (bi-directional) operation two MOSFETs are arranged back-to-back with their source pins tied together. Their drain pins are connected to either side of the output. The substrate diodes are alternately reverse biased to block current when the relay is off. When the relay is on, the common source is always riding on the instantaneous signal level and both gates are biased positive relative to the source by the photo-diode. It is common to provide access to the common source so that multiple MOSFETs can be wired in parallel if switching a DC load. Usually a network is provided to speed the turnoff of the MOSFET when the control input is removed. In AC circuits, SCR or TRIAC relays inherently switch off at the points of zero load current. The circuit will never be interrupted in the middle of a sine wave peak, preventing the large transient voltages that would otherwise occur due to the sudden collapse of the magnetic field around the inductance. This feature is called zero-crossover switching.

Figure 16: Conventional Relay

One of the main components of a solid-state relay (SSR) is an opto-isolator (also called an optocoupler) which contains one (or more) infra-red light-emitting diode, or LED light source, and a photo sensitive device within a single case. The opto-isolator isolates the input from the output. The LED light source is connected to the SSR’s input drive section and provides optical coupling through a gap to an adjacent photo sensitive transistor, Darlington pair or triac. When a current

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pass through the LED, it illuminates and its light is focused across the gap to a phototransistor/photo-triac. [19] Thus the output of an optocoupled SSR is turned “ON” by energizing this LED, usually with low-voltage signal. As the only connection between the input and output is a beam of light, high voltage isolation (usually several thousand volts) is achieved by means of this internal optoisolation. Not only does the opto-isolator provide a higher degree of input/output isolation, it can also transmit dc and low-frequency signals. Also, the LED and photo-sensitive device could be totally separate from each other and optically coupled by means of an optical fiber. The input circuitry of an SSR may consist of just a single current limiting resistor in series with the LED of the opto-isolator, or of a more complex circuit with rectification, current regulation, reverse polarity protection, filtering, etc.

Figure 17: DC input of Solid State Relay To activate or turn “ON” a sold state relay into conduction, a voltage greater than its minimum value (usually 3 volts DC) must be applied to its input terminals (equivalent to the electromechanical relay coil)[20]. This DC signal may be derived from a mechanical switch, a logic gate or micro-controller When using mechanical contacts, switches, push-buttons, other relay 46 | P a g e

contacts, etc, as the activating signal, the supply voltage used can be equal to the SSR’s minimum input voltage value, whereas when using solid state devices such as transistors, gates and micro-controllers, the minimum supply voltage needs to be one or two volts above the SSR’s turn-on voltage to account for the switching devices internal voltage drop. But as well as using a DC voltage, either sinking or sourcing, to switch the solid state relay into conduction, we can also use a sinusoidal waveform as well by adding a bridge rectifier for fullwave rectification and a filter circuit to the DC input.

The output switching capabilities of a solid state relay can be either AC or DC similar to its input voltage requirements. The output circuit of most standard solid state relays are configured to perform only one type of switching action giving the equivalent of a normally-open, single-pole, single-throw (SPST-NO) operation of an electro-mechanical relay.

Figure 18: Solid State Relay Output Circuit For most DC SSR’s the solid state switching device commonly used are power transistors, Darlington’s and MOSFETs, whereas for an AC SSR, the switching device is either a triac or back-to-back thyristors[22]. Thyristors are preferred due to their high voltage and current capabilities Some problems of conventional relay: 1. The directional feature is absented in electromagnetic relays 2. The speed of operation is limited by the mechanical inertia of the moving components

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3. Multifunctioning is not possible. One relay can perform only one function 4. The VA burden of these relays is higher than static and numerical relay

SSRs are ideal for a wide range of applications due to the following performance characteristics: 1.They provide high speed, high frequency ON/OFF switching operations. 2.Have no contacts failures 3.No arc noise 4.Output resistance remains constant regardless of amount of use Types of SSR It is convenient to classify the SSR by the nature of the input circuit and the classification is as follows: 1. Reed –Relay coupled SSR

Figure 19: Reed Relay SSR This type of SSR control signal is applied directly or using preamplifier to the coil of reed relay. This relay causes the operation of the trigger circuit which is used to trigger the power transistor or TRIAC.

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2. Transformer coupled SSR:

Figure 20: Transformer coupled SSR In this type, primary of low –power transformer is provided with the control signal, the thyristor switch is trigged by the secondary that is generated by the primary excitation.

3. Photo coupled SSR:

Figure 21: Photo coupled SSR In this type of relay a light or infrared source (generally LED) is provided with a control signal. A photo- sensitive semi- conductor device (diode, transistor or thyristor) detects the radiation from that source and generates an output. The output triggers the TRIAC which is used to switch the load current. The electrical isolation is excellent as the input and output path are coupled only by a beam of light. This type of SSR is discussed in detail below.

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Concept of Solid State Relay in this project Though the aim of this project is to design a digital relay so that we use here use Arduino board for our program installation and controlling the loads. For that reason, the SSR we used to be relate with the input of Arduino board. Block Diagram:

Figure 22: Solid State Relay Block Diagram From the above block diagram, we can see that the Arduino Digital pin is properly connected with the Solid-State relay and Solid-State relay consist POWER MOSFET, BJT, Capacitor, Resistor. SSR Algorithm The Solid-State Relay of this project following the mentioned algorithm: Step 1: When an excessive current flow from the line. Digital Pin of the MCU give a proper signal to the connected SSR certain transistor. Step 2: Transistor gives signal to the Power MOSFET for the switching Step 3: MOSFET switched and trip the connected load.

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SSR Working Flow Diagram

Figure 23: SSR Working Flow Diagram The SSR of this project worked properly moreover it can trip the connected certain load in proper time[21]. But there are some significant barrier or obstacles we face when we make this SSR. For that reason, we have to solutions all of those obstacles. The following obstacles are: 1. Adjusting the MOSFET switching time. 2. When an excessive over current flows MOSFET heated very rapidly. 3. Maintain fixed biasing voltage for the transistor. 4. Some delay from the MCU signal. For solving those obstacles, we take some initiatives so that we can overcome from those obstacles of the solid-state relay. 1. For proper switching from the MOSFET we use well design circuit. 2. Removing the heat from the MOSFET we use hit sink on MOSFET surface. 3. We make a proper circuit so that we can give biasing voltage of transistor from our main line. 4. Make an appropriate program for removing the delay from MCU signal.

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Some major applications of solid state relay SSR has gained favor in various regions that was earlier the domain of electromechanical relay or contactor. These are increasingly used in transformers, lamps, temperature control, solenoids, motors and valves etc. Few applications include the following:

-

3.2.2 Wireless Module (NRF24L01) For communication, the term wireless refers to transfer of information without using of any wires or electrical conductors. Wireless communication is one of the important mediums of transmission data or information to other devices. By various electromagnetic waves like RF (radio frequencies), infrared, satellite, etc. the data or information transmitted through the air in the wireless communication. In recent times, the wireless communication is placed in most cases of communication and it also significantly updated.

Figure 24: Wireless Module (NRF24L01) Advantages and Disadvantages of Wireless Communications Advantages



•

Any information can be conveyed or transmitted quickly and with a high speed.

•

The Internet can be accessed from anywhere and at any time without the need to carry cables or wires and it improves easy access and productivity.

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• 

Helpful for Doctors, workers and other professionals working in remote areas as they can be in touch with the medical centers through wireless communication.

•

Emergency situations can be alerted through wireless communication. The affected regions can be provided support with the help of these alerts through wireless



communication. •

Wireless networks cost less for installation and maintenance.

Disadvantages



•

A Hacker can easily capture the wireless signals that spread through the air.

•

It is very important to secure the wireless network so that the information cannot be exploited by unauthorized users, and this also increases the risk of losing data or information.

Figure 25: NRF24L01 along with antenna There are many wireless modules and technologies available in market. But we use for its basic advantages like ULP (Ultra Low Power) consumption, market availability, cheap rate and user friendly behavior. nRF24L01 in our project: Though this project is divided into some parts like in one part, here is used three senders for sending data and coordinator for receiving it. For sending and receiving

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data in this part nRF24L01 is used. In this project, there are three zones which are sending relevant data of current reading. In any abnormal condition of current, these send wireless signal. On the other hand, receiver or coordinator receives these data for further use. 3.2.3 Current Sensor (ACS712): Current Sensor: Current sensor is device that sense electricity in a conductor and makes a signal proportional to that current. The signal can be analog or digital. The Allegro ACS712 provides economical and precise solutions for AC or DC current sensing in industrial, commercial, and communications systems. The device package allows for easy implementation by the customer. Typical applications include motor control, load detection and management, switched-mode power supplies, and overcurrent fault protection. The device is not intended for automotive applications. For the automotive grade version.The device consists of a precise, low-offset, linear Hall sensor circuit with a copper conduction path located near the surface of the die. Applied current flowing through this copper conduction path generates a magnetic field which is sensed by the integrated Hall IC and converted into a proportional voltage. Device accuracy is optimized through the close proximity of the magnetic signal to the Hall transducer. A precise, proportional voltage is provided by the low-offset, chopper-stabilized BiCMOS Hall IC, which is programmed for accuracy after packaging.

Figure 26: Tested Circuit of ACS712 The internal resistance of this conductive path is 1.2 mΩ typical, providing low power loss. The do-it-yourself module described here is a simple carrier for Allegro’s ±20A ACS712 linear current sensor. This 5VDC operated little module accepts a bidirectional current input, and 54 | P a g e

outputs an analog voltage (66 mV/A) centered at 2.5 V (Vcc/2) with a typical error of less than 1.5%.Regulated 5VDC is required to power up the finished module. The red LED in the circuit indicates the presence of the input supply[28]. The nominal output voltage is 2.5VDC at zero current.

Figure 27: Current Sensor Module When DC load connected to the module draws current, this output voltage will deviate from 2.5V to either 0V or 5V depending on polarity of the connected load. However, note that to monitor an AC load you cannot use a DVM (or ADC of a microcontroller) directly.The output of the device has a positive slope (>VIOUT(Q)) when an increasing current flows through the primary copper conduction path (from pins 1 and 2, to pins 3 and 4), which is the path used for current sensing. The internal resistance of this conductive path is 1.2 mΩ typical, providing low power loss. The thickness of the copper conductor allows survival of the device at up to 5× overcurrent conditions. The terminals of the conductive path are electrically isolated from the sensor IC leads (pins 5 through 8).

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Figure 28: Simple pinout of ACS712 This allows the ACS712 current sensor IC to be used in applications requiring electrical isolation without the use of opto-isolators or other costly isolation techniques.The ACS712 is provided in a small, surface mount SOIC8 package. The leadframe is plated with 100% matte tin, which is compatible with standard lead (Pb) free printed circuit board assembly processes. Internally, the device is Pb-free, except for flip-chip high-temperature Pb-based solder balls, currently exempt from RoHS. The device package allows for easy implementation by the customer. Typical applications include motor control, load detection and management, switchedmode power supplies, and overcurrent fault protection. The device is not intended for automotive applications.

Figure 29: Real image of the current sensor ACS712 The device consists of a precise, low-offset, linear Hall sensor circuit with a copper conduction path located near the surface of the die. Applied current flowing through this copper conduction path generates a magnetic field that is sensed by the integrated Hall IC and converted into a

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proportional voltage. Device accuracy is optimized through the close proximity of the magnetic signal to the Hall transducer. A precise, proportional voltage is provided by the low-offset, chopper-stabilized BiCMOS Hall IC, which is programmed for accuracy after packaging. The ACS712 is provided in a small surface-mount SOIC8 package. The lead frame is plated with 100 percent matte tin, which is compatible with standard lead (Pb) free printed circuit board assembly processes. In this project ACS712 is used for sensing current. The ACS712 Current Sensors offered on the internet are designed to be easily used with micro controllers like the Arduino. These sensors are based on the Allegro ACS712 chip. These current sensors are offered with full scale values of 5A, 20A and 30A. 3.3 Server In a technical sense, a server is an instance of a computer program that accepts and responds to requests made by another program, known as a client. Less formally, any device that runs server software could be considered a server as well. Servers are used to manage network resources. For example, a user may setup a server to control access to a network, send/receive e-mail, manage print jobs, or host a website.

Figure 30: Images of Server Some servers are committed to a specific task, often referred to as dedicated. As a result, there are a number of dedicated server categories, like print servers, file servers, network servers, and database servers. However, many servers today are shared servers which can take on the responsibility of e-mail, DNS, FTP, and even multiple websites in the case of a web server. Because they are commonly used to deliver services that are required constantly, most servers are never turned off. Consequently, when servers fail, they can cause the network users and 57 | P a g e

company many problems. To alleviate these issues, servers are commonly high-end computers setup to be fault tolerant.

3.3.1 Examples of servers The following list contains links to various server types.

1.Application server 2.Blade server 3.Cloud server 4.Database server 5.Dedicated server 6.File server 7.Print server 8.Proxy server 9. Standalone server 10.Web server.

3.3.2 Some major components of server The hardware components that a typical server computer comprises are similar to the components used in less expensive client computers. However, server computers are usually built from higher-grade components than client computers. The following paragraphs describe the typical components of a server computer. MOTHERBOARD

The motherboard is the computer’s main electronic circuit board to which all the other components of your computer are connected. More than any other component, the motherboard is the computer. All other components attach to the motherboard. The major components on the motherboard include the processor (or CPU), supporting circuitry called the chipset, memory, expansion slots, a standard IDE hard drive controller, and input/output (I/O) ports for devices such as keyboards, mice, and printers. Some motherboards also include additional built-in features such as a graphics adapter, SCSI disk controller, or a network interface. PROCESSOR The processor, or CPU, is the brain of the computer. Although the processor isn’t the only component that affects overall system performance, it is the one that most people think of first when deciding what type of server to purchase. At the time of this writing, Intel had four processor models designed for use in server computers: Each motherboard is designed to support 58 | P a g e

a particular type of processor. CPUs come in two basic mounting styles: slot or socket. However, you can choose from several types of slots and sockets, so you have to make sure that the motherboard supports the specific slot or socket style used by the CPU. Some server motherboards have two or more slots or sockets to hold two or more CPUs.

Figure 31: Real Server The term clock speed refers to how fast the basic clock that drives the processor’s operation ticks. In theory, the faster the clock speed, the faster the processor. However, clock speed alone is reliable only for comparing processors within the same family. In fact, the Itanium processors are faster than Xeon processors at the same clock speed. The same holds true for Xeon processors compared with Pentium D processors [33]. That’s because the newer processor models contain more advanced circuitry than the older models, so they can accomplish more work with each tick of the clock. The number of processor cores also has a dramatic effect on performance. Each processor core acts as if it’s a separate processor. Most server computers use dual-core (two processor cores) or quad-core (four cores) chips. MEMORY Don’t scrimp on memory. People rarely complain about servers having too much memory. Many different types of memory are available, so you have to pick the right type of memory to match the memory supported by your motherboard [36]. The total memory capacity of the server depends on the motherboard. Most new servers can support at least 12GB of memory, and some can handle up to 32GB.

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Figure: Internal View of Server HARD DRIVES

Most desktop computers use inexpensive hard drives called IDE drives (sometimes also called ATA). These drives are adequate for individual users, but because performance is more important for servers, another type of drive known as SCSI is usually used instead. For the best performance, use the SCSI drives along with a high-performance SCSI controller card. [34] Recently, a new type of inexpensive drive called SATA has been appearing in desktop computers. SATA drives are also being used more and more in server computers as well due to their reliability and performance.

Figure: Server Connection NETWORK CONNECTION The network connection is one of the most important parts of any server. Many servers have network adapters built into the motherboard. If your server isn’t equipped as such, you’ll need to add a separate network adapter card. 60 | P a g e

POWER SUPPLY Because a server usually has more devices than a typical desktop computer, it requires a larger power supply (300 watts is typical). If the server houses a large number of hard drives, it may require an even larger power supply.

3.3.3 Advantages of using server A Server Adds Reliability It is highly likely that if any single component failed within your current shared computer (e.g power supply, hard drive, motherboard, etc) your files would be unavailable for however long it took to diagnose and repair/replace the failed component. This could potentially cost your company tens (or even hundreds if you have a lot of staff) of lost man hours in productivity while the repair / restore from backup to another machine is taking place [7].

A Server Gives Scalability Using a Windows XP Pro computer as a server has a hard-coded limit of 10 users able to simultaneously access it, and in most cases, the machine will start to respond sluggishly with more than 4 users accessing it.

A Server Makes for Faster Expansion With a server in place, adding new staff and computers can be highly automated. Creating network share mappings, installing printers, adding email addresses installing antivirus, setting up a facility to fax straight from within Word or other programs, all of this can be done using scripts and other tools to speed up deployment of new staff and equipment.

A Server Allows Centralized and Automated Backup Systems When not having a server in a business, there is a tendency to store data all over the place, and not have it properly backed up against deletion, corruption, fire and theft. Without a server, centralized email system like Microsoft Exchange, backing up company email is difficult and unreliable.

3.3.4 Server implementation in this project Implementing of server is one of the major work in this project. Implementing the server and maintain the server are main challenges in this project. We implemented the server for recording 61 | P a g e

the data and also continues monitoring each phase of the connected load. In this project, pcDuino is used as a server. Although pcDuino is as small as the size of a credit card, it works as if a normal computer at a relatively low price. it is possible to work as a low-cost server to handle light internal or web traffic. Grouping a set of pcDuino to work as a server is more cost-effective than a normal server. If all light traffic servers are changed into pcDuino, it can certainly minimize an enterprise’s budget. Actually, RPi uses software’s which are either free or open source. So, you’re learning atmosphere expands. It provides direct accessible processor pins as GPIOs. So, prototyping your vision project or learning computer science from scratch in such a device is better. One can learn in PC also but implementation at hardware level is not feasible as PC does not provide much hardware details. The processor if compared to its classs , then it is very good. It is a broadcom 900 MHz Quad core CPU. It is ARM Cortex A7 based device. RPi is known for the whole system as a whole. There are other products like Banana pi or orange pi having equal or better CPU capabilities but lacks somewhere in other support (like software integration with hardware). It is convenient to use RPi for beginning as it has very less software glitches and provides overall performance. Other products may have considered if it is known that a particular feature of that device has to be used extensively.

3.3.5 Principle of server in this project The main objective of implementing and using server in this project to continuous monitoring and recording the data from each phase. Each phase data’s (current, node id) are sending to the coordinator and after receiving the data from each phase coordinator send it to the certain server. Where server is able to decode the signal which it receives from the coordinator. After decoding the signal, it will show in the connected mentor with the server. So the server will operate always and it must be able to show all data which is coming from the coordinator. If an excessive current flow in the line than solid state relay must be operate and the data will send to server via coordinator.

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3.4 Overall Working Flow Diagram

Figure 32: Overall Working Flow Diagram of this project

The figure 32 shows, how the whole projects operate if we illustrate the overall working flow diagram we will see that the working flow diagram starts from the transmission or distribution side current, current enters the current sensor and current sensor is connected with the MCU. Then MCU will decide how the load will operate. It is important that each time the data will send to the coordinator and the coordinator will send the data to the server . From the server the side we are able to monitor the data simultaneously.

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Chapter-4 Project Outcome & Discussion

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4.1 Current Sensor (ACS712)

Performance Evaluation:The reference voltage and the supply voltage for the ACS712 and ACS713 are derived from the same voltage source, then both the ACS712 and ACS713 outputs and the A-to-D converter LSB track any variations in the reference voltage source. Therefore, reference voltage variations will not be a source of error in the analog-to-digital conversion of the ACS712 and ACS713 output signals.

Figure 33: Figure of Ip(A) Vs Vout(V)

Figure 4.1(a) is a plot of primary current, IP, versus output voltage, VOUT, of the ACS712ELC20A-T when varying VCC. The offset and sensitivity levels shift proportionally with VCC. For example, when VCC = 5.5 V, the 0 A output is 5.5 / 2 = 2.75 V nominal, and the sensitivity is 110 mV/A nominal.

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Figure 34: Typical ACS712 Die Temperature versus Continuous DC IP Current Figure 4.1(a) is a plot of primary current, IP, versus output voltage, VOUT, of the ACS712ELC20A-T when varying VCC. The offset and sensitivity levels shift proportionally with VCC. For example, when VCC = 5.5 V, the 0 A output is 5.5 / 2 = 2.75 V nominal, and the sensitivity is 110 mV/A nominal. Table 4.1: ACS712 Sustainable Pulsed DC Primary Current Rates Current

Pulse

Duty

Amplitude(A)

Duration(ms)

Cycle (%)

60

1000

10

120

20

10

200

10

10

200

10

1

100

10

10

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From the above table 4.1 we can say that, the sustainable DC primary current rates has some significant variations. If we give focus on the table 4.1 we could say easily, when the current 60A, the pulse duration 1000ms so the duty cycle remains 10%. When the current amplitude is 120A and 200A, the pulse durations are 20 and 10 respectively in both case the duty cycle remains same 10%. It is significant observation that when the current amplitude is 100A, pulse duration remain same 10ms and the duty cycle 10%. 4.2 Wireless Module (NRF24L01) Performance Evaluation: For evaluating the performance of wireless module we did two types of test, on air test and another is closed air test. The result of both those test as follow: Table 4.2(a): Data rate test on open air Distance (meter)

Speed

200

2 Mbps

400

2 Mbps

600

2 Mbps

800

1.5 Mbps

1000

250 kbps

From the above table, we can say that when the distance is 200- 600 meters the data rate is 2 Mbps. As there are no certain constraints on air so the data rate is very high as the distance is short but when the distance is above 600 meter we could say that the open air communication data rate is 1.5 Mbps. And we considered the maximum distance which is 1000 meter we see that on the open air we faced some constraints due to this the data rate is below 1.5 Mbps.

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Table 4.2(b): Data rate test on closed air Distance (meter)

Speed

200

1.5 Mbps

400

1.1 Mbps

600

0.5 Mbps

800

200 Kbps

1000

80 Kbps

From the above table we could say that on closed air the data rates are very much scattered and we have low data communication rate. As we see the closed air distance is 200 meter the data speed is 1.5 Mbps and when we increase the distance gradually we see that data rate becomes decreases> It is notified that when the closed air distance is 600 meter the data communication rate 0.5 Mbps . As the final distance are 800-1000 meter we could say that 200 Kbps and 80 Kbps respectively. 4.3 Project Performance Evaluation By gradually increase the current of the distribution side up to 5A we saw the time of operation of the relay. Table 4.3: Project Performance Evaluation Current (Amp)

Time of operation (sec)

0.25

1.95

0.49

1.80

0.60

1.52

0.75

1.49

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0.80

1.20

1.00

1.01

1.25

0.94

1.50

0.87

1.75

0.70

2.00

0.65

2.25

0.60

2.50

0.55

2.75

0.49

3.00

0.45

3.25

0.41

3.50

0.36

3.75

0.30

4.00

0.26

4.25

0.20

4.50

0.16

4.75

0.11

5.00

0.08

Using the above data, we draw the below curve by MATLAB. We clearly observe here that, after gradually increase the current the time of operation of relay become decreasing. Here, we draw the relay curve of the distribution side

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Figure 35: IDMT Behaviour Curve Gradually increasing the operating current the operating time of the relay frequently decreasing, which very much similar with the IDMT relay behaviour. Here, X= Applied Current Y=Operating Time. However, the below figure shows the simultaneous data monitoring from the server side. And from the server side we can monitor and record the data at a time. If we give light, on below figure we will see that from the server side we are able to figure out the conditions of each phase. For instance, it’s important for us that we are successfully able to know each zone conditions from our server side.

Figure 36: Data observing from the server side

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4.4 Cost Analysis Cost analysis is the main goals to make our device cost effective and efficient system for Nano grid with the existing solar home system. As our device is for rural areas of the world where the main grid is still an exaggerated dream. For this reason, in many cases we have sacrificed simplicity. Whenever we faced an option we analysed each of them in terms of both cost effectiveness and efficiency. Table 4.4: Cost Analysis Chart Parts

Cost(TK)

Arduino Nano

1600

Current Sensor

600

Wireless Module

800

Boards

550

PcDunio

9500

Other Equipment’s

700

Our device consists Arduino Nano, Wireless Module NRF24L01, Current Sensor ACS712 and for server PCDUINO.so the cost assumption of the project has been broken down in Table 4.4. All the calculated considering the retail price of components.

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Chapter-5 Achievement and Motivation

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Fuel cells and many small-scale renewables natively generate low voltage DC power. Most of these generators supply power to AC mains networks and require costly and inefficient power invertors; even where the power may ultimately be delivered to a DC device. A possible solution is to install a DC network linking DC devices to DC power supplies. Such networks have not yet emerged because of the higher electrical losses associated with transmitting a fixed amount of power as low voltage DC, rather than higher voltage AC. But with the proliferation of low power electronic devices, bringing the potential for LEDs to reduce lighting loads by a up to a factor of 10 and the potential for efficient distributed power generation, localized DC networks – or DC micro grids - may finally be practical. Aside from reducing resource and financial costs, a key advantage of DC microgrids is that the low risk of dangerous electric shocks from low voltage DC makes plug-and-play grids a possibility. This greatly reduces the installation cost of micro-generation, and could empower end users to take responsibility for understanding and controlling their individual energy consumption. Adding intelligence and internet connectivity to DC micro-grid controllers further enables consumer engagement with AC mains devices - through smart metering and ultimately with dynamic demand management. And this could reduce costs associated with periods of high and low power consumption.

5.1 Purposes and Architecture of DC grid system Following three terms are briefly summarized purposes of the DC micro grid system. (1) Increase the introduction of distributed PV units. (2) Reduce energy dissipation and facility costs resulting from AC/DC conversion by integrating the junction between a commercial grid and DC bus which connects PV units and accumulators. (3) Supply power to loads via regular distribution lines (not exclusive lines for emergency) even during the blackout of commercial grids.

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Figure 37: Schematics Diagram of a DC grid System Figure 37, shows a schematic view of the DC micro grid system. This system utilizes a DC bus as its backbone and distributes power to a community that consists of several dozens or a hundred of households in a residential area. A 350 V DC bus is installed instead of 200 V / 100 V lines in conventional AC distribution systems and connected with a high voltage commercial grid through the intermediary of a bidirectional AC/DC converter. All the PV units in the community are linked with the DC bus through DC/DC. converters. These converters always track the maximum power point of the DC power sources which fluctuates depending on the intensity of solar radiation. Conventional appliances can be used as they are if an inverter is installed in each house to change the DC power into 200V / 100 V AC power, but DC power feeding will spread widely because of its high efficiency, once safe and compact gears, such as breakers and outlets, are standardized in the future. Storage batteries of the community are also linked to the DC bus. The DC-based distribution system reduces facility costs and energy dissipation associated with AC/DC conversion because the PV units and battery are DC connected and most of the current energy-saving appliances operate on DC due to the progress of inverter technology. This is why we should push ahead with the DC system. The system doesn’t require long transmission lines to convey solar power from remote areas because the PV units have been distributed in the demand area. Power sources and loads are

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closely located to each other in a community. The excess and deficiency of power are variable factors which should be compensated for a good balance between supply and demand. [19] The DC grid is also resistant to disasters. Even under conditions where electric power and fuel are not supplied from outside, we can have electric power sources. At the time of the power failure of the commercial grid, the DC micro grid works as an independent power source that is disconnected from the commercial grid. Since power is fed to loads via regular distribution lines, exclusive lines for emergency are unnecessary. In such a situation, power supply needs to be regulated to continue the independent operation; however, people who live in the same community would cooperate to make the best use of the limited power.

5.2 Applications There are significant applications in this project. The applications are as below:

1. Design is well applicable for any DC grid. 2. Ensured the protection of the DC grid transmission & distribution side. 3. Applicable for reducing the unexpected interfering in the DC grid line.

5.3 Future Scope

Some future improvement also can be done by small modification of the system. For instance,

1. Planning to upgrade the systems for any grids. 2. Making more cost effective. 3. Developing the project for controlling the phase line from authority office after trip the certain connected load. 5.4 Challenges

▪ ▪

To protect the DC grid’s both transmission and distribution side from different kinds of electric fault. There is no remote monitoring and control system. 75 | P a g e

Conclusion There are many protection devices in electrical system and those electrical devices mainly invented due to give the proper protection of the electrical system. Now considering the perspective of the modern world growing and moving so dynamically and electrical system such as dc grid systems surely make a great impact. It is important that how we control the electrical systems. If the control is so much swift and frequent than it will be very much effective. This project main aim is to give proper protection to the dc grid transmission line and also the distribution side. As the main concern of this project is dc grid so it is important to get the sufficient knowledge about the dc grid. Although we have many protective devices in AC grid but we have not sufficient and cost effective protective device in dc grid. This project is very much applicable for any dc grid and also in the sense of cost this project is very much effective also. At the begging of our project we had done a survey where we saw that due to the continuous increase of load, overcurrent fault has been arising not only that no certain monitoring system for observing current of each phase from the grid plant authority office and load current increase by some unexpected interruption by the locality. It is very significant for us that our project is successfully able to do monitoring and recording the data. And this project is very much effective for dc grid transmission line as well as distribution line. For instance, we were able to do some momentous observations such as when the transmission line current or distribution side current gradually increase the operating time of the relay become decreasing. In the economical point of view, this project is very much cost effective. So, we could easily say that this project is viable. We had done some software simulation in Porteous to see the MOSFET switching. For practical implementation in this project we were very much careful, when MOSFET switched there are some spike voltage and we reduce this spike voltage by snubber circuit. We used two types of snubber circuit in this project OFF state and ON state. The significant part of this project is that we are able to simultaneous monitor each distribution phase pf the dc grid line. In addition, we can easily save and record those data for further study. To conclude, we could say that considering every stage, every point of view and every angle of social life this project is able to make a huge impact in the upcoming modern time.

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References [1] REN21,

“Renewables

2017

Global

Status

Report”

[Online].

Available:

http://www.ren21.net/status-of-renewables/global-status-report/ [2]

Paroma Jahan, Nusrat Chowdhury, and Md Khondoker Abu, “Diesel-PV mini grid system for Rural Household loads in a nono grid area of Bangladesh”, UIU, Defense 2010, pp 2-3

[3] BPDB, “Solar Power Project” [Online]. Available: http://www.bpdb.gov.bd/bpdb/index.php?option=com_content&view=article&id=26 [4] Sparkfun, “pcduino”[Online]. Available : https://www.sparkfun.com/ [5] SREDA,” Renewable Energy”[Online]. Available: http://www.sreda.gov.bd/ [6]

Shahriar Ahmed Chowdhury ,and Shakila Aziz, “Solar-diesel hybrid energy model for Base Transceiver Station (BTS) of mobile phone operators” , Developments in Renewable Energy Technology (ICDRET), 2012 2nd International Conference on the, 5-7 Jan. 2012.

[7]

Shahriar Ahmed Chowdhury, Shakila Aziz, Sebastian Groh, Hannes Kirchhoff, and Walter Leal Filho, “Off-grid rural area electrification through solar-diesel hybrid minigrids in Bangladesh: resource-efficient design principles in practice” , Journal of Cleaner Production, 15 May 2015, pp

194-202. [8]

Detlef Bahnemann, “Photocatalytic water treatment: solar energy applications” , Solar Energy, November 2004, pp 445-459.

[9] ElectronicsTutorials, “ Solid State Relay” [Online]. Available: http://www.electronicstutorials.ws/power/solid-state-relay.html [10] OMRON , “Difference between SSRs and Mechanical Relays”[Online]. Available: https://www.ia.omron.com/support/guide/18/overview.html [11] Panasonic, “SSR Principle of Operation” [Online]. Available: https://www3.panasonic.biz/ac/ae/control/relay/solid-state/principle_operation/index.jsp [12] Y. Ito, Y. Zhongqing, and H. Akagi, “DC microgrid based distribution power generation system” ,

Power Electronics and Motion Control Conference, 2004. IPEMC 2004. The 4th International , 14-16 Aug. 2004. [13] D.C. Martins , and R. Demonti, “Grid connected PV system using two energy processing stages” ,

Photovoltaic Specialists Conference, 2002. Conference Record of the Twenty-Ninth IEEE, 19-24 May 2002 [14] Xiong Liu , Peng Wang , and Poh Chiang Loh “A Hybrid AC/DC Microgrid and Its Coordination

Control” , IEEE Transactions on Smart Grid ( Volume: 2, Issue: 2, June 2011 ), 17 March 2011,pp278 – 286 [15] Henry’s Bench, “ACS712 Current Sensor Manual” [Online]. Available: 77 | P a g e

[16]

http://henrysbench.capnfatz.com/henrys-bench/arduino-current-measurements/acs712-current-sensoruser-manual/

[17] ARDUINO, “Arduino Nano”.[Online]. Available: https://www.arduino.cc/en/Main/ArduinoBoardNano [18] Gustavo Gamboa, Christopher Hamilton, and Ross Kerley “Control strategy of a multi-port,

grid connected, direct-DC PV charging station for plug-in electric vehicles” , Energy Conversion Congress and Exposition (ECCE), 2010 IEEE, 12-16 Sept. 2010. [19] Yu-Kai Chen, Yung-Chun Wu, and Chau-Chung Song , “Design and Implementation of Energy

Management System With Fuzzy Control for DC Microgrid Systems”, IEEE Transactions on Power Electronics ( Volume: 28, Issue: 4, April 2013 ), 26 July 2012,pp-1563 – 1570 [20] J.M. Carrasco ,L.G. Franquelo, and J.T. Bialasiewicz “Power-Electronic Systems for the Grid

Integration of Renewable Energy Sources: A Survey” , IEEE Transactions on Industrial Electronics ( Volume: 53, Issue: 4, June 2006 ), 07 August 2006 pp- 1002 – 1016 . [21] Electronics Hub, “Wireless Communication: Introduction, Types and Applications”[Online].Available: http://www.electronicshub.org/

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Appendix Wireless Module (NRF24L01) Key Features NRF24L01 has a great contribution in the wireless communication. Therefore, we have to know all the important features of NRF24L01. From the Nordic Semiconductor document, we can find those features. Features are as follow: • Radio Worldwide 2.4GHz ISM band operation 126 RF channels Common RX and TX pins GFSK modulation 1 and 2Mbps air data rate 1MHz non-overlapping channel spacing at 1Mbps 2MHz non-overlapping channel spacing at 2Mbps • Transmitter Programmable output power: 0, -6, -12 or -18dBm 11.3mA at 0dBm output power • Receiver Integrated channel filters 12.3mA at 2Mbps -82dBm sensitivity at 2Mbps -85dBm sensitivity at 1Mbps Programmable LNA gain

• RF Synthesizer Fully integrated synthesizer No external loop filer, VCO varactor diode or resonator Accepts low cost ±60ppm 16MHz crystal • Enhanced ShockBurst™ 1 to 32 bytes dynamic payload length Automatic packet handling Auto packet transaction handling 6 data pipe MultiCeiver™ for 1:6 star networks 79 | P a g e

• Power Management Integrated voltage regulator 1.9 to 3.6V supply range Idle modes with fast start-up times for advanced power management 22uA Standby-I mode, 900nA power down mode Max 1.5ms start-up from power down mode Max 130us start-up from standby-I mode • Host Interface 4-pin hardware SPI Max 8Mbps 3 separate 32 bytes TX and RX FIFOs 5V tolerant inputs • Compact 20-pin 4x4mm QFN package 2.2.2 Applications of NRF24L01

NRF24L01 add a great track in the wireless communication era for that reason the application of this device widely speared in recent time. The significant application of NRF24L01 are as follow: • Wireless PC Peripherals • Mouse, keyboards and remotes • 3-in-one desktop bundles • Advanced Media center remote controls • VoIP headsets • Game controllers • Sports watches and sensors • RF remote controls for consumer electronics • Home and commercial automation • Ultra low power sensor networks • Active RFID • Asset tracking systems

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Pin Assignment of NRF24L01 In NRF24L01 there are 20 pins and each pin are important for the communication of data and also the maintain stable power supply in the device. So, we have to know about the essential pin assignment of this device. For better understand we considered here the block diagram of the NRF24L01. Block diagram of NRF24L01 given below.

Fig-6: NRF34L01 block diagram

From the Fig-6, we see the block diagram of the NRF24L01, now we present here the functions of all pin of the NRF24L01. Pin functions are given below: Table 4: NRF24L01 Pin Function PIN

Name

Pin Function

Description

1

CE

Digital Input

Chip Enable Activates RX or TX mode

2

CSN

Digital Input

SPI Chip Select

3

SCK

Digital Input

SPI Clock

4

MOSI

Digital Input

SPI Slave Data Input

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5

MISO

Digital Input

SPI Slave Data Output, with tristate option

6

IRQ

Digital Input

Maskable interrupt pin. Active low

7

VDD

Power

Power Supply (+1.9V - +3.6V DC)

8

VSS

Power

Ground (0V)

9

XC2

Analog Output

Crystal Pin 2

10

XC1

Analog Input

Crystal Pin 1

11

VDD_PA

Power Output

Power Supply Output(+1.8V) for the internal nRF24L01 Power Amplifier

12

ANT1

RF

Antenna interface 1

13

ANT2

RF

Antenna interface 2

14

VSS

Power

Ground (0V)

15

VDD

Power

Power Supply (+1.9V - +3.6V DC)

16

IREF

Analog Input

Reference current

17

VSS

Power

Ground (0V)

18

VDD

Power

Power Supply (+1.9V - +3.6V DC)

19

DVDD

Power Output

Internal digital supply output for de-coupling purposes.

20

VSS

Power

Ground (0V)

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Arduino Nano Technical Specifications Microcontroller

ATmega328

Architecture

AVR

Operating Voltage

5V

Flash Memory

32 KB of which 2 KB used by bootloader

SRAM

2 KB

Clock Speed

16 MHz

Analog I/O Pins

8

EEPROM

1 KB

DC Current per I/O Pins

40 mA (I/O Pins)

Input Voltage

7-12 V

Digital I/O Pins

22

PWM Output

6

Power Consumption

19 mA

PCB Size

18 x 45 mm

Weight

7g

Product Code

A000005

Terminal List Table Pin No.

Name

Type

Description

1-2, 5-16

D0-D13

I/O

Digital input/output port 0 to 13

3, 28

RESET

Input

Reset (active low)

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4, 29

GND

PWR

Supply ground

17

3V3

Output

+3.3V output (from FTDI)

18

AREF

Input

ADC reference

19-26

A0-A7

Input

Analog input channel 0 to 7

27

+5V

Output or Input

30

VIN

PWR

+5V output (from on-board regulator) or +5V (input from external power supply) Supply Voltage

Current Sensor (ACS712) Selection Table: Part Number

TA (°C)

Optimized Range, IP (A)

Sensitivity, Sens (Typ) (mV/A)

ACS712ELCTR-05B-T

–40 to 85

±5

185

ACS712ELCTR-20A-T

–40 to 85

±20

100

ACS712ELCTR-30A-T

–40 to 85

±30

66

Absolute Maximum Ratings Characteristic Supply Voltage Reverse Supply Voltage Output Voltage Reverse Output Voltage Output Current Source Output Current Sink Overcurrent Transient Tolerance Nominal Operating Ambient Temperature Maximum Junction Temperature Storage Temperature

Symbol V CC V RCC V IOUT V RIOUT I

Notes

Rating 8 –0.1 8 –0.1

Units V V V V

3

mA

10

mA

100

A

–40 to 85

ºC

165 –65 to 170

ºC ºC

IOUT(Sou

I

rce) IOUT(Sin

k) IP

1 pulse, 100 ms

A

Range E

T

TJ(max) T stg

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Isolation Characteristics Characteristic

Symbol

Dielectric Strength Test Voltage*

V

Working Voltage for Basic Isolation

V

Working Voltage for Reinforced Isolation

V

ISO

WFSI

WFRI

Notes Agency type-tested for 60 seconds per UL standard 60950-1, 1st Edition For basic (single) isolation per UL standard 60950-1, 1st Edition For reinforced (double) isolation per UL standard 60950-1, 1st Edition

Rating

Unit

2100

VAC

354

VDC or Vpk

184

VDC or Vpk

Terminal List Table Number

Name

Description

1 and 2

IP+

Terminals for current being sampled; fused internally

3 and 4

IP–

Terminals for current being sampled; fused internally

5

GND

6

FILTER

Terminal for external capacitor that sets bandwidth

7

VIOUT

Analog output signal

8

VCC

Signal ground terminal

Device power supply terminal

Common Operating Characteristics Characteristics Symbol Electrical Characteristics Supply Voltage VCC Supply Current ICC Output CLOAD Capacitance Load Output Resistive RLOAD Load Primary Conductor RPRIMARY Resistance Rise Time tr

Test Conditions

Min. Typ.

Max.

Units

VCC = 5.0 V, output open VIOUT to GND

4.5 – –

5.0 10 –

5.5 13 10

V mA nF

VIOUT to GND

4.7

–

–

kΩ

TA = 25°C

–

1.2

–

mΩ

IP = IP(max), TA = 25°C,

–

3.5

–

μs 85 | P a g e

Frequency Bandwidth Nonlinearity Symmetry Zero Current Output Voltage Power-On Time

f ELIN ESYM VIOUT(Q) tPO

COUT = open –3 dB, TA = 25°C; IP is 10 A peak-to-peak Over full range of IP Over full range of IP Bidirectional; IP = 0 A, TA = 25°C Output reaches 90% of steady-state level, TJ = 25°C, 20 A present on leadframe

–

80

–

kHz

– 98 –

1.5 100 VCC ×0.5 35

– 102 –

% % V

–

μs

12 1.7

– –

G/A kΩ

Max. 85

Units °C

Value 5

Units °C/W

23

°C/W

–

–

Magnetic Coupling Internal Filter RF(INT) Resistance

Common Thermal Characteristics

Operating Internal Leadframe Temperature Junction-to-Lead Thermal Resistance Junction-to-Ambient Thermal Resistance

TA

E range

Min. –40

Typ. –

RθJL

Mounted on the Allegro ASEK 712 evaluation board RθJA Mounted on the Allegro 85-0322 evaluation board, includes the power consumed by the board

x30B PERFORMANCE CHARACTERISTICS Characteristic

Symbol

Optimized Accuracy Range

IP

Test Conditions

Min. Typ.

Max.

Units

–30

30

A

–

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Sensitivity

Sens

Noise

Zero Current Output Slope

Sensitivity Slope

Total Output Error

63

66

69

mV/A

VNOISE(PP) Peak-to-peak, TA = 25°C, 66 mV/A programmed Sensitivity, CF = 47 nF, COUT = open, 2 kHz bandwidth

–

7

–

mV

ΔVOUT(Q)

TA = –40°C to 25°C

–

–0.35 –

mV/°C

TA = 25°C to 150°C

–

–0.08 –

mV/°C

TA = –40°C to 25°C

–

0.007 –

mV/A/°C

TA = 25°C to 150°C

–

– – 0.002

mV/A/°C

IP =±30 A, TA = 25°C

–

±1.5

ΔSens

ETOT

Over full range of IP, TA = 25°C

–

%

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