A Solution to Remote Detecting of Illegal Electricity Usage Based on Smart Metering A. Pasdar, S. Mirzakuchaki, Industrial and Science University of Iran
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Abstract— Power line carrier communication presents new area for automatic meter reading, by equipped energy meter with power line system all user connect each other with this communication method, Smart metering uses all potential of this communication channel to presents new service in low voltage distribution grid. by installing smart meter detection system for detect illegal usage of electricity may be easily added to distribution network, in this method by sending test signal at high frequency in network, software calculates line impedance that connect each two energy meters, by comparing the data that related to installation time with other times data, system can find and locate place of illegal usage of electricity.
Index Terms—Smart meter, Automatic meter reading, find illegal usage of electricity
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I. INTRODUCTION
HE automatic meter reading (AMR) systems has been installed in many countries and use by many energy suppliers , this system introduced to make ability for remote reading of customer’s energy consumption [1]. AMR is based on different communication technique for transferring data to long distance. Wireless and power line carrier communication are two economical solution for automatic meter reading, but power line carrier communication is more economical solution in cooperation with wireless system [2][3][4]. Power line carrier communication (PLC) is a kind of technique to transmit data over power line in low voltage side. In PLC we modulate data over specific carrier frequency and transmit it over power line, so every users who connected to low voltage side of power line in the same phase can act as data node. If an AMR system may be established in a power network every user connected each other via power line. Because of powerful ability that such system provides to us we can introduce new system that be more than just meter reading, this system is famous as smart metering. Smart metering provides more ability in supplies network, such as transferring of command and more data. In this effort we want to introduce a new approach for detect and find illegal connection in power line grid based on smart metering.
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Illegal usage of electricity is a big problem in many countries. In such usage user make a illegal connection to electricity grid and him/ her connection doesn’t pass throw a meter, so without any payment he or she can use energy. Illegal usage of electricity has two major disadvantage, from a economical point of view this usage of electricity destroy suppliers budget ,because they provide energy to many node without any return ,just in turkey, energy and natural resource minister said that 19% of total electricity consumption in turkey is illegal [5]. He went on to say: “illegal use was around 12% in 1997, which is equivalent to 8.8 billion kilowatt per hour. This is worth more than $500 million.” Up to now we talk about economical disadvantage of this usage of electricity, but the another major problem is technological disadvantage. Electrical grid design for specific volume of customers, this grid can provide specific kilowatt hour energy for costumer and illegal usage of electricity can cause a critical technical problem for suppliers, and planning of national energy may be difficult in the case of unrecorded usage. This kind of usage may be a serious problem in many countries like turkey, as we know this problem has been attempted to be resolved in many countries such Iran, the methods like security, police, etc. This method could not give the optimum solution due to their impracticalities; this study attempt to talk about solution to solve illegal usage of electricity problem based on smart metering and developed meters. II. DETECTION OF ILLEGAL ELECTRICITY USAGE A. History [5] In October 2004 Hakki cavdar suggest a new method for detection of illegal usage based on automatic meter reading. First we talk about his hypothesis to describe better of his new method. He assume that illegal usage of electricity may be happened in following ways. 1) Using the mechanical objects: A subscriber can use some mechanical objects to prevent the revolution of a meter, so the disk speed is reduced and the recorded energy is also reduced.
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SOFA 2007 • 2nd IEEE International Workshop on Soft Computing Applications • 21–23 August, 2007 • Gyula, Hungary – Oradea, Romania
2) Using a fixed magnet: A subscriber can use a fixed magnet to change the electromagnetic field of the current coils. As we know, the mechanical energy meter is based on the electromagnetic field. 3) Using the external phase before meter terminals: This method gives subscribers free energy without any record. 4) Switching the energy cables at the meter connector box: In this way, the current does not pass through the current coil of the meter, so the meter does not record the energy consumption.
Fig. 1. electricity
Cavdar’s method for illegal usage of
As cavdar said first two methods are valid for mechanical meter and in digital meter subscriber cants use energy in illegal way, but the last two method are valid for both mechanical and digital energy meters. The proposed system for detection of illegal usage of electricity is shown in fig. 1. power line carrier signal can transfer only in low voltage side of distribution transformer, and PLC signal’s that blocked in transformer cant’ pass it, so this topology must be repeated for each transformer. In his method each energy meter is equipped with PLC modems and digital energy meter IC. PLC modem must be send and receive data via power line by modulating or demodulating data over or from carrier frequency that travel over power line 220v signal, PLC signaling must be in CENELEC or FCC standards, EN50065-1 is formed by CENELEC, and frequency bands and signaling level for each usage is shown. 3-95KHz are restricted for use by electricity suppliers, and 95-148.5KHz are restricted to consumer use. The signal level at this band has regularity limitation. For general use, the signaling level is limited to 116μv, and for particular applications, e.g., industrial areas, the signaling level is limited to 134μv, the recorded data in energy meter send to central room via PLC modem. In transformer site a main energy meter records the total energy that use in grid. Cavdar method based on this recorded data, if the energy that the main energy meter show , be higher than the addition of each customer energy meter then system detect a illegal usage of
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electricity , because some energy usage don’t record by the legal energy meter, because those energy don’t pass energy meter’s to use, in his method each energy meter has one energy meter IC like ade7751,so the energy record both in mechanical and digital way, he assume that if mechanical part for any reason cant calculate right energy value, then the mechanical recorded data and digital unit recorded data have difference with each other , so the energy suppliers can easily find the energy meter that had stroked [ 6]. In many cases, in which some one using extra cable before mechanical part terminal, if we assume that the digital unit be before this illegal connection his method can show the illegal connection, but in many cases and many countries such India the illegal node in many cases connect directly to power line of street and the load feed directly from main power line without any energy meter and any record of energy consumption data. From a reality point cavdar’s method is only valid for detecting illegal usage of electricity in one low voltage grid, but for showing the place of illegal connection this method in many cases has now usage, in this effort we want to introduce new way for finding a place of illegal electricity usage based on smart metering. B. New method for finding an illegal connection
Fig. 2. Smart metering block diagram
The new method that we want to describe is based on smart metering. In fig. 2. the basic block diagram of smart meter is shown, as you see in fig. 2. this kind of energy meter has more ability than just automatic meter reading, one unit of smart meter act as traditional AMR, this unit measure energy consumption based on mechanical measuring or digital measuring. In mechanical kind measurement is based on disk and electromagnetic field. In mechanical AMR an optical sensor use for detection of disk movement, this sensor send digital pulse to microcontroller unit, and a counter in microcontroller of energy meter counts disk routing, by counting the disk routing system can measure energy
A. M. Pasdar, S. Mirzakouchaki • A Solution to Remote Detecting of Illegal Electricity Usage Based on Smart Metering
consumption. In digital AMR the energy meter IC such ade7751 calculates energy consumption based on voltage and current data that received from current and voltage transformer. Relay is another part of smart meter, by using this unit energy suppliers can turn on or off energy meter from distance without any physical attempting, the control command send from energy supplier via power line carrier signal. For finding place of illegal node in this method we need to have access to turn on or off energy meter’s C. Method description In this method we use power line characteristic to determine the illegal node. Table I [7] Low voltage power line characteristic
grid, operator send special command to system for disconnect, at this time all the energy meter in grid must be disconnect from main voltage, so we have only some inductor in grid, if we have specific impedance at the end of the grid, at this moment little current follow in the mesh, because of energy meter disconnection this current only has relation with end grid impedance. Power line impedance is very little at 50 Hz, in this method for grid characteristic record we send 2v at 150 KHz signal against 220V at 50 Hz, because of energy meter disconnection this sending hasn’t any side effect. At 150 KHz signal the power line has good impedance per meter, the power line impedance at this frequency must be about 1ȍ / m , so by smart meter analog to digital converter we can read different voltage at different node. Imagine a grid with three energy meter, each energy meter connect to another energy meter with 10m cable.
D.Reactance Electronic Resistance Image Files Al/Fe,mm² (Optional) KV line ȍ/Km(50Hz) ȍ/Km(+20˸ c ) You will have the greatest control over the appearance of your figures if you are able to prepare electronic image files. 0.30 1.06 25.0 0.4 Over head If you do not have the required computer skills, just submit paper above 0.28 prints as described 0.64 50.0and skip this 0.4 section. Over head 1) Easiest Way: If you have a scanner, the best and quickest way to0.87 prepare non-color files isOver to print 0.10 35.0 figure 0.4 head As you see in table I the reactance of over head power line is very negligible at 50 Hz, in short distance like our grid the capacitance of line is very negligible although in high frequency and the line act only as a inductor [8][9][10][11]. The reactance of inductor shown in equation 1 reac tan ce 2SfL (1) As we shown in equation 1 the reactance of inductor has direct relationship with frequency, so if we work at higher frequency the value of this reactance must be higher than reactance at 50Hz. if we assume the reactance of overhead power line be .3 ȍ per kilometer at 50 HZ, this value must be 0.9 per meter at 150 KHz. Photographs and grayscale figures should be prepared with 220 dpi resolution and saved with no compression, 8 bits per pixel (grayscale). To obtain a 3.45-in figure (one-column width) at 220 dpi, the figure should have a Color figures should be prepared with 400 dpi resolution
Fig. 4. Spice simulation circuit
Fig. 5. Simulation result for grid at normal situation and 150 kHz test signal sending
Fig. 3. sample low voltage grid In fig. 3. basic low voltage grid is shown, power line is shown as inductors and load in costumer’s home is shown as impedance. After installation of smart meter in low voltage
Fig. 4. Show example circuit with three node for simulation, the inductor’s value considered for 10m cable, and end grid impedance is steed to 1 kȍ. At first we send 2v at 150 KHz signal to grid. In fig. 5. simulation result is shown, as you see in the simulation result node voltage have sensible difference with each, and the pick to pick of node voltage is about common analog to digital converter, but at
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SOFA 2007 • 2nd IEEE International Workshop on Soft Computing Applications • 21–23 August, 2007 • Gyula, Hungary – Oradea, Romania
220 signal it is very difficult to build high resolution analog to digital converter. So by 150 KHz test signal we can easily record node voltage at the installation time. Because we now the current that follow in grid when we send test signal, by applying node voltage and famous ohm law we can find impedance of each line that connect to energy meter to each other, we save those impedance for each to node in our database. Now imagine one illegal connection is in our grid, this illegal connection may have two positions: 1) if someone use extra phase before his or her energy meter the illegal node is parallel with legal node. 2) if someone connect his or her load directly to main power line of street the illegal node must be between to legal node.
from main and only illegal node is in grid, so the impedance of line that connect to this node at our software after sending test signal must be changed, so we easily find illegal node at the map.
Fig. 7b. Illegal node when node be between two legal node
Fig. 6. Example of one illegal connection in grid or when this node be paralleled with illegal node
In fig. 7b. the illegal node is between two legal node this means that someone connect his or her load directly o the main power line of street. At the example we divide the cable that connect energy meter number one to energy meter number two to inductor and connect the illegal node to division point.
Fig. 6. show example for illegal node when this node is paralleled with legal node. We assumed at this simulation that the illegal impedance be 100 ȍ and this illegal node paralleled with energy meter number 2. now we re simulate this grid by following legal voltage from node one to end node and compare those voltage with recorded voltage we can understand that at illegal node the impedance of power line was changed, because all legal node was disconnected Fig. 8. simulation result for illegal node that connected between to legal node.
Fig. 7. Simulation result for kind one of illegal connection position
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As shown in fig. 8. The node voltage that we record when sending test signal is changed. Now if we read node voltage and imagine that we have only one illegal node, by applying the current that follow to grid and node voltage we can recalculate the new impedance of between two nodes. By comparing the new impedance and recorded impedance we can determine the two node that illegal node is between them, and show it on map. At this method we need two kind of smart energy meter 1) The energy meter that installed at costumer’s home. This smart meter must has ability to disconnect the
A. M. Pasdar, S. Mirzakouchaki • A Solution to Remote Detecting of Illegal Electricity Usage Based on Smart Metering
2)
home’s load from main voltage by receiving the disconnection command from server. Also this smart meter must has ability two read the RMS voltage of test signal that it reads. The smart meter that install at center transformer. This smart meter must has ability to generate test signal and disconnect grid from main voltage and send test signal to grid, this smart meter also must has ability to read the current that follow in grid when that test signal is sent. D. Method steps
1) when grid is installed , disconnect all load and main voltage from grid and send test signal to grid 2) record all node voltage and the main current that follow from main energy meter to the grid 3) calculate impedance of each line that connect to energy meter and save those impedance by nods name in the database 4) at normal operation of grid , compare the total power that use in grid by reading main energy meter, to addition of all energy meter value, if those two value have difference you find illegal usage at your grid, if this cooperation step repeat in short period of time you can detect illegal usage at the first connection of it. 5) After detect illegal usage disconnect all load from main and main voltage by ending off command to grid 6) Send test signal to grid 7) Read all node RMS voltage and current that follow to grid from main energy meter 8) By applying the detection method that explain above you can find the place of illegal node
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III. CONCLUSION By using smart meter and basic software for monitoring the low voltage grid, energy supplier can monitor their grid easily and find the place of illegal energy usage in their grid if this problem existed.
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