Microcontroller Based Automatic PFI Plant Design
National Conference on Electronics for Digital Society 2014 Paper ID #: I-III 07
Design of a Microcontroller Based Automatic Power Factor Improvement Plant for Power System Protection Laboratory Muhibul Haque Bhuyan* and Debashis Das Department of Electrical and Electronic Engineering Green University of Bangladesh, Mirpur 2, Dhaka, Bangladesh Department of Electrical and Electronic Engineering Bangladesh University of Engineering and Technology, Dhaka, Bangladesh
26 June 2014
*E-mail:
[email protected], Cell #: 01815-657346 Contact Author: Prof. Dr. Engr. Muhibul Haque Bhuyan Professor and Chairperson, Department of EEE, Green University of Bangladesh
Slide # 1 of Total 25 Slides
Microcontroller Based Automatic PFI Plant Design
Outline of the Presentation • Objectives • Introduction
• Design Process • Working Principles
• Results • Conclusions • Future Works 26 June 2014
Contact Author: Prof. Dr. Engr. Muhibul Haque Bhuyan Professor and Chairperson, Department of EEE, Green University of Bangladesh
Slide # 2 of Total 25 Slides
Microcontroller Based Automatic PFI Plant Design
Objectives of the Work
• To design microcontroller based automatic power factor improvement plant for the EEE department of Green University of Bangladesh • To minimize the cost of design
• To design few undergraduate experiments
26 June 2014
Contact Author: Prof. Dr. Engr. Muhibul Haque Bhuyan Professor and Chairperson, Department of EEE, Green University of Bangladesh
Slide # 3 of Total 25 Slides
Microcontroller Based Automatic PFI Plant Design
Introduction… • Most loads in modern electrical distribution systems are inductive, such as, • • • • • •
Motors Fan Blowers Refrigerators Air-conditioners Induction heating furnaces etc.
• Inductive loads require two kinds of power: 1) real power to produce the desired output of the machine and 2) lagging reactive power to sustain the electromagnetic field of the load
• Phasor sum of real and reactive power produce apparent power 26 June 2014
Contact Author: Prof. Dr. Engr. Muhibul Haque Bhuyan Professor and Chairperson, Department of EEE, Green University of Bangladesh
Slide # 4 of Total 25 Slides
Microcontroller Based Automatic PFI Plant Design
…Introduction… • The ratio of the working power (P) to the apparent power (S) is called power factor (cosf) or alternatively cosine of the phase angle difference between load voltage and load current is called power factor (cosf) as per definition of IEEE 1459-2010 standard • If reactive power (Q) increases then power factor becomes low
Power Triangle
Vector Diagram
E S
IX f I 26 June 2014
cos f
V IR
P S
Q
f
Contact Author: Prof. Dr. Engr. Muhibul Haque Bhuyan Professor and Chairperson, Department of EEE, Green University of Bangladesh
P Slide # 5 of Total 25 Slides
Microcontroller Based Automatic PFI Plant Design
…Introduction… • Normally, the power factor of the whole load on a large generating station is above 0.9 • However, sometimes due to heavy inductive loading power factor becomes less than 0.9 causing the lower power factor of the load • Low power factor causes • • • • •
To increase transmission line current To increase transmission line drops To increase transmission line losses To decrease load voltage and increase voltage regulation To reduce transmission efficiency
• Thus low power factor is undesirable from economic point of view • In order to improve the load power factor, some device that takes leading reactive power should be connected in parallel with the load • Hence it is necessary to study the various means of improving the power factor 26 June 2014
Contact Author: Prof. Dr. Engr. Muhibul Haque Bhuyan Professor and Chairperson, Department of EEE, Green University of Bangladesh
Slide # 6 of Total 25 Slides
Microcontroller Based Automatic PFI Plant Design
…Introduction… • At present, many public and private universities in Bangladesh have established Electrical and Electronic Engineering (EEE) Department due to the high demand of this subject at home and abroad. In their curriculum, both theory and laboratory course on ‘Power System Protection’ is mandatory for the students who take Power as major. • But the establishment of Power System Protection Laboratory for the EEE department is a big challenge due to the huge expenditures • To establish a Power System Protection Laboratory, we need to purchase various costly equipment, such as, Power Factor Improvement (PFI) plant, over and under voltage protector, over and under current protector, over and under frequency protector, over and under temperature protector, auto-re-closer etc. from different foreign manufacturers. • PFI plant is one of the most important equipment to study automatic power factor improvement process in industries; and in this work, we designed a low cost PFI plant using microcontroller 26 June 2014
Contact Author: Prof. Dr. Engr. Muhibul Haque Bhuyan Professor and Chairperson, Department of EEE, Green University of Bangladesh
Slide # 7 of Total 25 Slides
Microcontroller Based Automatic PFI Plant Design
…Introduction… With the development of technology, microcontroller is becoming more suitable chip to control various electro-mechanical devices
Microcontrollers are used in automatically controlled products and devices By reducing the size and cost, microcontrollers make it economical to digitally control even more devices and processes simultaneously
26 June 2014
Contact Author: Prof. Dr. Engr. Muhibul Haque Bhuyan Professor and Chairperson, Department of EEE, Green University of Bangladesh
Slide # 8 of Total 25 Slides
Microcontroller Based Automatic PFI Plant Design
…Introduction… This work is aimed at developing a low cost microcontroller based automatic power factor improvement plant for the EEE department of Green University of Bangladesh (GUB) When the load power factor falls below its predefined value (in this case, unity) then the microcontroller sends the signal to turn on capacitors from a bank of capacitors to improve the power factor
26 June 2014
Contact Author: Prof. Dr. Engr. Muhibul Haque Bhuyan Professor and Chairperson, Department of EEE, Green University of Bangladesh
Slide # 9 of Total 25 Slides
Microcontroller Based Automatic PFI Plant Design
…Introduction In fact, static capacitors are used invariably in industries or factories to improve the power factor of the industrial loads. The capacitor draws a leading current and partly or completely neutralizes the lagging reactive component of load current. This raises the power factor of the load. S
Power Triangle
Vector Diagram
E IX
IC
QC
f
V
f I/
S/
P I
26 June 2014
Q
IR
Contact Author: Prof. Dr. Engr. Muhibul Haque Bhuyan Professor and Chairperson, Department of EEE, Green University of Bangladesh
QC
Slide # 10 of Total 25 Slides
Microcontroller Based Automatic PFI Plant Design
Design Process… The power factor improvement (PFI) plant has three primary sections, such as, 1) Inductive load 2) Capacitor bank as the reactive power compensator and 3) Automatic controller section using microcontroller.
26 June 2014
Contact Author: Prof. Dr. Engr. Muhibul Haque Bhuyan Professor and Chairperson, Department of EEE, Green University of Bangladesh
Slide # 11 of Total 25 Slides
Microcontroller Based Automatic PFI Plant Design
…Design Process…
3-f Bus Bar
3-fsupply
Capacitor Bank
3-fCircuit Breaker CT
Six Magnetic Contacts
3-f Induction Motor (Load)
VL PC of C CC of C
IL
Microcontroller (PF Regulator)
Relays
Block diagram of the power factor improvement plant 26 June 2014
Contact Author: Prof. Dr. Engr. Muhibul Haque Bhuyan Professor and Chairperson, Department of EEE, Green University of Bangladesh
Slide # 12 of Total 25 Slides
Microcontroller Based Automatic PFI Plant Design
CT
To Microcontroller Circuit Breaker
Magnetic Contacts
3-f Cables Circuit Breaker
Inductive load is designed using the following parts: 1) Bus bar 2) Inductive load (three 3-phase induction motors) 3) Circuit Breakers 4) Push Buttons (green and red colors) 5) Lamps (yellow color)
HRC Fuse
Bus Bars
…Design Process…
Capacitors and Relays
To 3-f Supply Induction Motors
Inside view of power factor improvement plant 26 June 2014
Contact Author: Prof. Dr. Engr. Muhibul Haque Bhuyan Professor and Chairperson, Department of EEE, Green University of Bangladesh
Slide # 13 of Total 25 Slides
Microcontroller Based Automatic PFI Plant Design
CT
To Microcontroller Circuit Breaker
Magnetic Contacts
3-f Cables Circuit Breaker
On the other hand, compensation circuit has been designed using the following parts: 1) Bank of Capacitors (Y-connected, 3-phase) 2) Magnetic contacts 3) Relays 4) HRC Fuses 5) Lamps (red color)
HRC Fuse
Bus Bars
…Design Process…
Capacitors and Relays
To 3-f Supply Induction Motors
Inside view of power factor improvement plant 26 June 2014
Contact Author: Prof. Dr. Engr. Muhibul Haque Bhuyan Professor and Chairperson, Department of EEE, Green University of Bangladesh
Slide # 14 of Total 25 Slides
Microcontroller Based Automatic PFI Plant Design Red Lamp Indicators for Capacitor Bank
Yellow Lamp Indicators for Induction Motor
…Design Process… Microcontroller
Automatic controller section is designed using the following components: 1) Microcontroller as the power factor regulator 2) Current transformer 3) Magnetic contacts 4) Relays
Green Push Buttons to Start Motors
Red Push Buttons to Stop Motors
Front view of power factor improvement plant 26 June 2014
Contact Author: Prof. Dr. Engr. Muhibul Haque Bhuyan Professor and Chairperson, Department of EEE, Green University of Bangladesh
Slide # 15 of Total 25 Slides
Microcontroller Based Automatic PFI Plant Design
…Design Process… Frame is designed using steel sheet. Bus bar section is designed using three copper bars. Three cables are connected with three bus bars to connect it to the three phase power supply through circuit breaker.
Three 3-f induction motors of different ratings are connected to the bus bars through three magnetic contacts.
26 June 2014
Contact Author: Prof. Dr. Engr. Muhibul Haque Bhuyan Professor and Chairperson, Department of EEE, Green University of Bangladesh
Slide # 16 of Total 25 Slides
Microcontroller Based Automatic PFI Plant Design
…Design Process… Three groups of capacitors are used as compensators. Each group consists of three 1-f capacitors in parallel. All Normally Open (NO) contacts of the relay are connected to the microcontroller to be fed from its output signal to switch ON or OFF the capacitors.
High Rupturing Capacity (HRC) fuses, capable of withstanding high current and short circuit faults, are used to avoid accidental short circuit problems of capacitors.
Front view of power factor improvement plant 26 June 2014
Contact Author: Prof. Dr. Engr. Muhibul Haque Bhuyan Professor and Chairperson, Department of EEE, Green University of Bangladesh
Slide # 17 of Total 25 Slides
Microcontroller Based Automatic PFI Plant Design
…Design Process Red Lamp Indicators for Capacitor Bank
Yellow Lamp Indicators for Induction Motor
The microcontroller is fitted on the front panel of the steel frame along with the various lamps and push buttons. Three red lamps are used to indicate which bank of capacitor is turned on whereas yellow lamps indicate which motor is running. Green and red push buttons are used to start and stop the induction motors respectively.
Microcontroller
Green Push Buttons to Start Motors
Red Push Buttons to Stop Motors
Front panel of power factor improvement plant 26 June 2014
Contact Author: Prof. Dr. Engr. Muhibul Haque Bhuyan Professor and Chairperson, Department of EEE, Green University of Bangladesh
Slide # 18 of Total 25 Slides
Microcontroller Based Automatic PFI Plant Design N
Working Principle…
L1 L2
Microcontroller Power Microprossor Based Controlled Factor Regulator IC
Unit
L3 CT L2
L3
MC-1 MC-2
MC-3 Common
3 Pase CB Fuse
Microcontroller gets the line-to-line input voltage from the bus bar and line current through the secondary of the current transformer (CT). Microcontroller has an in-built program that can calculate the phase angle between the load voltage and load current and hence the load power factor and displays on LCD screen of the controller.
Partial circuit diagram of microcontroller based power factor improvement plant. 26 June 2014
Fuse CT Ratio -2:1
Magnetic Megnatic Contact Contructor
C=17.5 Mfd
MC.Coil-1
Magnetic Megnatic Contact Contructor
C=35 Mfd
MC .Coil-2
Magnetic Megnatic Contact Contructor
C=52.5 Mfd
MC .Coil-3
Variable Inductive load (L)
(R)
Fixed Resistive Load
Microprocessor Contorlled Power Factor Improvement Plant( PFI)
Contact Author: Prof. Dr. Engr. Muhibul Haque Bhuyan Professor and Chairperson, Department of EEE, Green University of Bangladesh
Slide # 19 of Total 25 Slides
Microcontroller Based Automatic PFI Plant Design
…Working Principle The control relay allows a variety of possible settings to meet the condition on site. If it is close to the set value then no further capacitors are added or removed. If the power factor is still below its set value then the controller adds more capacitors with the load and thus tries to establish the set value of the power factor.
If the power factor becomes leading but its value is close to the set value then the controller releases few capacitors from the load by exporting the extra leading reactive volt-amperes (VARs) to the bus bar. The process is continued at an adjustable time delay (TD) interval till the unity power factor (PF) is achieved. Both time delay (TD) and power factor (PF) can be set by using the arrow keys on the front panel of the.
When the load is turned off then the capacitors are released in reverse order by exporting the leading reactive volt-amperes (VARs) to the bus bars gradually. 26 June 2014
Contact Author: Prof. Dr. Engr. Muhibul Haque Bhuyan Professor and Chairperson, Department of EEE, Green University of Bangladesh
Slide # 20 of Total 25 Slides
Microcontroller Based Automatic PFI Plant Design
Output
Red Lamp Indicators for Capacitor Bank
Yellow Lamp Indicators for Induction Motor
LCD Monitor of Microcontroller
Array Buttons for Adjusting PF and TD
Result of power factor improvement is shown in the screen of the panel 26 June 2014
Contact Author: Prof. Dr. Engr. Muhibul Haque Bhuyan Professor and Chairperson, Department of EEE, Green University of Bangladesh
Slide # 21 of Total 25 Slides
Microcontroller Based Automatic PFI Plant Design
Test Data… Power Factor Motor #
26 June 2014
After start After 10 sec After 10 sec After 10 sec of the load
1
0.73 lagging 0.18 leading 0.98 lagging
-
2
0.67 lagging 0.89 lagging 0.98 lagging
-
3
0.54 lagging 0.69 leading 0.83 lagging 0.92 lagging
1+2
0.60 lagging 0.73 lagging 1.0 lagging
2+3
0.49 lagging 0.57 lagging 0.69 lagging 0.95 lagging Contact Author: Prof. Dr. Engr. Muhibul Haque Bhuyan Professor and Chairperson, Department of EEE, Green University of Bangladesh
-
Slide # 22 of Total 25 Slides
Microcontroller Based Automatic PFI Plant Design
Conclusions A very low cost microcontroller based automatic power factor improvement (PFI) plant has been designed PFI plant is tested from the Power System Protection Laboratory of the Department of EEE of GUB The test run shows that the designed plant is working very well The cost is optimized and is very low as compared to the imported PFI plant Thus it is possible to save foreign currency 26 June 2014
Contact Author: Prof. Dr. Engr. Muhibul Haque Bhuyan Professor and Chairperson, Department of EEE, Green University of Bangladesh
Slide # 23 of Total 25 Slides
Microcontroller Based Automatic PFI Plant Design
Future Scopes • PFI plant can be used in • Industries where loads are inductive
• It can be redesigned for single phase circuit/load • PFI plant can be designed using microprocessor/ DSP/ FPGA/ PLC also
26 June 2014
Contact Author: Prof. Dr. Engr. Muhibul Haque Bhuyan Professor and Chairperson, Department of EEE, Green University of Bangladesh
Slide # 24 of Total 25 Slides
Microcontroller Based Automatic PFI Plant Design
THANK YOU VERY MUCH for your kind presence
26 June 2014
Contact Author: Prof. Dr. Engr. Muhibul Haque Bhuyan Professor and Chairperson, Department of EEE, Green University of Bangladesh
Slide # 25 of Total 25 Slides
