Based on Load Shedding 1

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2011 IEEE PES Innovative Smart Grid Technologies – India

978-1-4673-0315-6/11/$26.00©2011 IEEE

Remote Detection of Illegal Electricity Usage Employing Smart Energy Meter

–A Current Based Technique

Suman Deb#1,Pankaj Kumar Bhowmik #2,Arik Paul#3

Deptt. of Electrical Engg National Institute of Technology,Silchar Assam,Pin: 788010

INDIA [email protected] , 2

[email protected],[email protected]

Abstract — At present, illegal usage of electricity is a serious

problem facing the power industry in many countries. An

efficacious and worthwhile solution to counteract this

problem can be realized by using:

a) already existing electrical network for communication

i.e. PLC(Power Line communication)

b) smart metering system.

In the prototype of detection system presented in this paper, test signal at high frequency is transmitted through

the network and software at supplier’s end compares data

with reference data. Based on the outcome of this

comparison, it can remotely be detected if there is any

illegal electricity usage or not. The study documented in

this paper puts forward a new and unprecedented current-

based technique to tackle the problem of illegal electricity

usage. This paper reveals the existence of very small line

current during the detection test which proves to be the

key to unlock the problem of illegal electricity usage

detection.

Keywords-smart energy meter,line inductance, loaddisconnection, illegal node, critical load

I . I NTRODUCTION

Saving and using energy more efficiently is gradually gainingmore and more prominence as the availability of energy isdecreasing. A major problem faced in power distribution todayis the illegal usage of electricity. It is a serious problem inmany countries, especially in the developing and theunderdeveloped nations such as those of the Indian sub-continent .Despite all efforts the rate of electricity theft inTurkey increased from 14.4 percent in 17.7 percent from 2008to 2009, recent data from Turkish Electricity Distribution

Company has shown. Pakistan loses Rs.80 billion annually onaccount of electricity theft [3]. Karachi Electric SupplyCompany (KESC) and Hyderabad Electric Supply Company(HESCO) have been facing the worst state of electricity theft.In HESCO , line losses due to theft figure more than 40 %with KESC competing the figure closely[4].In India pilferage

(power theft) is responsible for the disappearance of 29% ofthe electricity generated. In energy terms this amounts to613.87 million units/ day[5]. In such usage, user makes anillegal connection to electricity grid and his/ her connectiondoesn‘t pass through a meter, so without paying any electric bill he or she can use energy. Such illegal usage of electricityhas two major disadvantages. At first, from an economic point

of view this usage of electricity destroys supplier‘s budget, because they provide energy to many nodes without any profitreturn. Another major problem confronted by the energyregulatory boards is its technological disadvantage. Electricalgrid design for distribution side is planned and prepared takinginto consideration specific volume of consumers and theirenergy demands. According to strategic planning, any grid can provide specific kilowatt-hours of energy for consumers andsuch illegal usage of electricity can cause a critical technical problem for suppliers, and hence planning of national energymay be difficult in the case of unrecorded consumption,ultimately resulting in the inefficient operation of the powersystem.

To counteract this problem a smart metering system canserve the purpose of detecting the illegal electricity guzzling indemand side. A smart metering system includes a smart meter,communication infrastructure, and control devices. Smartmeter is an advanced form of energy meter which can collectaccurate readings of energy consumption and feedbackadditional information to the utility company (as well asconsumers) in contrast to a conventional energy meter.




Figure.1 shows an architectural difference of a simple energymeter and a smart meter. A smart energy meter has thecapability of real-time registration of electricity usage and possibly electricity generated, offering the feature of readingthe meter both remotely as well as locally. Smart meters cancommunicate bi-directionally and execute control commands

remotely as well as locally.The main aim of this work is to provide a solution to the problem of illegal electricity usage , similar to those whichhave been performed earlier in this direction.

II. BENEFITS OF SMART METERING R ELATED TO E NERGY

SAVINGS

Under normal conditions, when the consumers are connectedto the power supply via the smart energy meter, the benefitsassociated with smart metering are [6]:

Remote collection of meter data facilitates theminimization of data collection cost, eliminates

estimated bills and provides accurate data for usageinformation on bills.

Smart meters will provide consumers with much

more elaborate information on their energy usage,either on their bills, via the internet or directly within

their homes, or a combination of all of these.Signals from the smart metering system can be usedas a tool to control energy management processeswithin the property, allowing further cost reduction.

Remote management of meters will remove thedifficulty of meter operators to physically visit metersand eliminate problems associated with gainingaccess to meters.

It also helps with remote switch-on/off functionalityto reduce safety risks and energy consumption onunused premises.

III. DETECTION OF ILLEGAL ELECTRICITY USAGE

A. Ways of illegal electricity usage

In the distribution side of power system, illegal usage ofelectricity may happen in following ways [7]:

1) A consumer can use some mechanical objects to retard or prevent the revolution of disc of a meter, so the disc speed is

reduced and hence the recorded energy is less than the actualvalue.

2) A consumer can change the electromagnetic field of thecurrent coils (as we know, the mechanical energy meter is based on the electromagnetic field) with the help of a fixedmagnet, thereby reducing the energy consumption recorded.

3) By using the external phase before meter terminals,consumers can subscribe free energy without any record.

4) Illegal users can switch the energy cables at the meterconnector box to prevent the flow of current through thecurrent coil of the meter, so the meter does not record theenergy consumption.In countries like India, illegal users steal electricity directlyfrom the main power line of street by using hook-like

electrical connector to supply power to various electricalappliances.

B. New method proposed for detecting an illegal node

The new method described in this paper follows a current based approach using one of the features of smart energymetering system. Figure 2 depicts the basic functionalelements of a smart energy meter.

As can be seen in Fig. 2, smart energy meter providesconsumers with more features than just automatic meterreading. One unit of smart meter functions as conventionalAMR- this unit indicates energy consumption based onmechanical or digital measurement. Mechanical measurementis based on the principle of rotation of disc caused by theinteraction of two electromagnetic fields. In mechanical AMRa sensor senses the rotation of disc and generates digital pulseto be transmitted to the microcontroller unit. A counter in themicrocontroller keeps a count of the number of rotations of thedisc, thereby measures the number of units of energy

consumed. In digital AMR the energy meter IC calculatesunits of energy consumed based on voltage and current datareceived from CT and PT.As mentioned earlier, remote switchON/OFF functionality is possible with the help of relay-another part of smart meter, the control command being sentfrom energy provider via power line carrier signal.




ReactanceΩ/Km(50 Hz)

ResistanceΩ/Km(+20ºC)

Al/Femm²

Kv Line

0.30 1.06 25.0 0.4 OHDL*

0.28 0.64 50.0 0.4 OHDL*

0.10 0.87 35.0 0.4 OHDL*

C. Operation

In this method, power line characteristic is used to determinethe presence of illegal node.

Table 1: Low Voltage Power Line Characteristics [8]

*Over-Head Distribution Line

Table 1 shows that the reactance of over head power lineis negligible at 50 Hz. In case of short line, the linecapacitance is not appreciable.In high frequency, the

capacitive reactance (= 1/ ) becomes negligibly smalland so, the line acts only as an inductor [9][10][11] [12].

Figure 3: Basic Low Voltage Grid

In the above figure, distribution line is shown as series oflumped inductors and consumer‘s load as impedance. After

installation of smart energy meter in low voltage grid, suppliersends special command signal to smart energy meteringsystem to disconnect the consumer‘s load from the distributionline, so we have only inductive distribution line. Now, in grid,if we have specific impedance at its end, a little current flowsin the mesh. Because of energy meter disconnection, thiscurrent has relation only with end grid impedance. In thismethod, for distribution line characteristic record, we send 2Vsignal at 150kHz instead of 220V signal at 50Hz. Sinceconsumer loads have been disconnected, this high frequencysignal transmission has no side effect. At 150kHz, the line hasconsiderable impedance (=2 L) per metre. Line impedanceat this frequency must be approximately 1Ω / m. Consider agrid with three energy meters, each energy meter connected toanother energy meter with 10m cable.

Figure 4 is the circuit representation of the considered gridwith three energy meters, the values of inductance betweentwo consecutive nodes being for 10m cable and the end gridimpedance as 1k Ω. At first we transmit 2V signal at 150 kHzto grid, all loads being remotely disconnected from mainvoltage by receiving the disconnection command from server.The smart meter installed at distribution transformer should

have the ability to read the current flowing through thedistribution line when test signaling is being done. Using thissmart meter, the value of the current flowing through the lineduring the test signaling period is measured and serves as thereference value. This reference value is noted at the time ofgrid installation and stored in the database.

The smart meter installed at the distribution transformershould be able to measure current flowing in grid duringdetection test. In this detection method, the prime utility of thissmart meter is measuring the line current during detection test.

The smart energy meters utilized in our detection scheme must

have the feature of allowing their ground connections switchedON/OFF through remotely generated command signals. Theadvantage of this feature is that it facilitates better comparisonof current values obtained during detection tests with thereference one.




Figure 6 : ―Line Current v/s load impedance at illegal node plot

During detection test, the first step is to switch OFF the

ground connections of the smart energy meters as well asdisconnect their respective loads from main line with the helpof remotely generated command signals as shown in Figure 6. Now, 2V test signal at 150kHz is transmitted through theisolated line. The resulting line current is easily measured bythe central smart energy meter. The measured value iscompared with the reference value obtained at the time of gridinstallation. If there is no illegal node, both values aremeasured to be same.

Now, by considering an illegal node to be present betweenL2 and L3, we(using NI LABVIEW) plot a graph betweenRMS values of line current(simulated using NI MULTISIM)during test period v/s corresponding values of loadimpedance(R in figure 5) at illegal node. Here, the referencevalue is simulated to be 67.498 nanoAmps.

The effectiveness of our current based approach in detectingthe presence of illegal node is evident from the graph (shownin figure 6) due to the presence of steep downward slopingregion .As a result, there is a drastic fall in the value of linecurrent for a very small change in the value of impedance atillegal node. This results in a remarkable difference betweenthe reference value and the observed value, thereby, making iteasier for the software at the supplier control room to detectillegal usage.

However, during simulation of the RMS line current values, itwas observed that for a very small value of 0.02285 Ω illegalload impedance, the line current came out to be same as thereference value, thereby making it impossible to detect the presence of illegal load around this value. This value can betermed as ‗ critical load‘. But, owing to the extreme smallnessof this impedance value in power system, this anomaly hasnegligible effect in reducing the practical effectiveness of thismethod.

In our second case, referring to figure 7, an illegal node is placed between L1 and L2. Following detection procedure asabove, we obtain the same reference value as earlier.

Following graph is obtained from the simulated values:

The graph for this case features presence of similar steepdownward sloping region. The critical load for this position ofillegal node is 0.028090Ω - small enough to be neglected.

Hence, this method is effective irrespective of the position of

illegal node in the grid.

IV. CONCLUSION

By using smart meter and basic software for monitoring thelow voltage grid, energy supplier can monitor their grid easilyand find the presence of illegal energy usage in their grid ifthis problem existed using line current as the detection parameter.




V. R EFERENCES

[1] S.S.S.R.Depuru, L.Wang, V.Devabhaktuni,N.Gudi, Smart Meters for Power

Grid- Challenges,Issues,Advantages and Status , 2011 IEEE

[2] R.V.Gerwen, S.Jaarsma,R.Wilhite, ―Smart Metering, July 2006 /http://www.leonardo-energy.org

[3] http://www.khaleejtimes.com ,5 April 2007.

[4] http://www.nation.com.pk/pakistan-news-newspaper-daily-english-online/Politics/13-

May-2010/Govt.-fails-to-control-power-theft

[5] ―Revolutionary Concept of Power Management , slide from http://www.google.com

[6] J.C.P.Kester, M.J.G.Burgos, J.Parsons ―Smart Metering Guide-Energy Saving and theCustomer Edition 2010 p.7,8,9.

[7] H. Cavdar, ―A solution to remote detection of illegal Electricity usagevia power line communications, IEEE Trans. Power delivery, vol.19,N). 4, October 2004.

[8] E. Lakrvi, and E. J. Holmes―Electricity distribution network design , p. 37

[9] M. Tanaka, ―High frequency noise power spectrum, impedance and

transmission loss of power line in Japan on intrabuilding power linecommunication), 1988 IEEE

[10] M. Tanaka, ―Transmission characteristics of a power line used for datacommunications at high frequencies, 1989 IEEE

[11] M. P. Sanders, Power line carrier channel & application considerationfor transmission line relaying, Pulsar technologies M. P. Sanders, Power line carrier channel & application consideration for transmission

line relaying, Pulsar technologies Inc.

[12] W. Sado, and J. Kunicki ―Personal communication on residential power line – assessment of channel parameters , IEEE

VI. BIOGRAPHY

Mr Suman Deb was born on 30.08.1989. He is at present pursuing B.Tech in Electrical Engg . from National Institute of Teechnology, Silchar (India). His research interests are in digital electronics, computer aided power systems and energy management

Mr Pankaj Kr. Bhowmik was born on 21.04.1990.He is at present pursuuing B.Tech in Electrical Engg. from National Institute ofTechnology,Silchar(India).His research interests are in control system , power systems, renewable energy resources,

Instrumentation, Signal Processing

Mr Arik Paul was born on 21.09.1991. He is at present pursuing B.Tech in Electrical Engg. from National Institut of Technology, Silchar (India). His research interests are in power electronics , smart grid technology and energy management.

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