POWER THEFT DETECTION VIA PLC

            The automatic meter reading(AMR) system as become a necessity for most suppliers as deregulation, free customer choice and open market competition occur in the energy supply sector. Power line communication has many new service possibilities on the data transferring via power lines without use extra cables. AMR is a very important application in these possibilities due to every user connected each other via modems using power lines. AMR is a technique to facilitate remote readings energy consumption.

                 Improving the electrical power supply to households as a big issue. The government has set a specific goal to raise the distribution rate of electrical power supply, which is now around 70% to 80% to 100%.  Power companies are plagued by power theft. PLC will play an important role in placing anti-theft power system.

                 Illegal electricity may be a serious problem in many countries .This problem has been attempted to be resolved by special skills of humans, such as the police special security etc. These method could not give optimum solution due to their impracticalities. Meter reading has been applied by humans and some electronics solutions such as optical reading methods, creditable utilization of electrical energy etc.

                 Many chips which can be used for digital energy metering and PLC modems. The problem of illegal usage of electricity must be solved electronically, without any human control.

2. POWER THEFT

                 Electrical power by altering, slowing, resetting, swapping, or disconnecting an electric meter. Theft also may occur by rewiring circuits to avoid an electric meter, or by tapping into another customer’s electrical lines. The fraudster might use devices to program the theft of power only during certain periods of theday or week. A fraudster may rewire their property to illegally use power from cheaper sources of power, or from meters that are billed at lower rates. The fraudster risks electrocution and detection. Field employees of the power company are trained to spot problems that result in persons not being billed for all the electricity they use. Computerized billing systems are designed to detect erratic electricity use

3. PLC installATION.

               Power meters with PLC modules will be installed near the top of the power polls.  Previously, it was enough to install power meters in high places, not in low places such as the  house wall, to prevent users from using power  illegally by connecting cables, or by using  tampered meters. However, by doing so, the homeowners themselves cannot check how much electricity was used. Therefore, PLC technology was chosen.  Meters installed in high places will send data of the used amount to each household through power lines. Homeowners can then check the  amount used on the displays installed in each  house. This means that the measurement function and the display function of the meters will be separated.

Each power meter is connected to an optical fiber network, and information of the amount used by each household is sent to the power companies. If the power companies find that a payment is delinquent, they can remotely stop the power supply by controlling the meters through the optical fiber network. In this way, HD-PLC and optical fiber networks enable power companies to prevent power theft, and to grasp the actual amount of power consumed by district or by each household in real time, and also to control the amount of power supply. The waste of power can also be reduced, another big advantage. Furthermore, wide spread use of the power meters with HD-PLC modules is expected to reduce regional disparities in information, or the ‘digital divide’.

4 . DETECTION OF ILLEGAL ELECTRICITY USAGE

4.1 Methods Of  Illegal Electricity Usage:

         In illegal usage, a subscriber illegally use electricity in following ways:

4.1.1 Using the mechanical objects:

 A subscriber can use some mechanical objects to prevent the revolution of a meter, so that disk speed is reduced and the recorded energy is also reduced.

4.1.2 Using a fixed magnet:

A subscriber can use a fixed magnet to change the electromagnetic field of the current coils. As is well known , the recorded energy proportional to electromagnetic field.

4.1.3. Using the external phase before meter terminals:

         This method gives subscribers free energy without any record.

4.1. 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.

  Although all of the methods explained above may be valid for electromechanical meters, only the last two methods are valid for digital meters.

5. DESCRIPTION ON PLC

                  Most economically viable technology for transferring Meter data to DCU. Uses the technique of communicating the data over existing Electrical Lines which carry LT power to the site. PLC is a kind of communication technology, which uses Medium Voltage(MV) and Low Voltage(LV) distribution network as the communication media to implement transmission of data, voice and real time image.

The components involved in PLC are the;

1.      Power Line Carrier Unit which provides signal transmission and reception.

2.      There is a  Coupler used for “clamping” around a live wire thus injecting the communication signals into the power line.

3.      PLC modem

  5.1 The monitoring system mainly has the following functions:

1.      Remote meter-reading

2.      Data acquisition

3.      .Thread PLC transmissions are synchronized to the zero crossing point of the AC power line. It should be transmitted as close to the zero crossing point i.e. within 200 μs. Square wave with a max Delay of 100 μs from the zero crossing point The maximum delay between signal envelope input and 120KHz output bursts is 50 μs. Therefore, it should be arranged that outputs to the within 50 μs.

5.2 CODE  TRANSMISSION:

         A Binary 1 is represented by a 1 ms burst of 120 KHz the zero crossing point and a Binary 0 by the absence of 120 KHz. Therefore only the 1 ms "envelope" need be applied to their inputs.

         These 1 millisecond bursts should actually be transmitted three times to coincide with the zero crossing points of all three phases in a three phase distribution system.

7.     DEFINITION ON AMR

  AMR(AUTOMATIC REMOTE READING) automates the process of measurement through digital communication techniques.

Bring “intelligence” into the revenue cycle and manage it:

The revenue cycle includes metering, billing operating, customer and the services. 

7.1 ADVANTAGES:

1.      Smart automated process instead of manual work.

2.      Accurate information from the network load to optimise maintenance and investments

3.      Customized rates and billing dates.

4.      Streamlined high bill investigations.

5.      Detection of tampering of Meters.

6.      Accurate measurement of transmission losses.

7.      Better network performance and cost efficiency.

8.      Demand and distribution management.

9.      More intelligence to business planning

10.  Better company credibility.

9. DETECTION

         The recorded data in kilowatt hour meters for every subscriber are sent to host PLC modem via PLC modems which are placed in subscribers locations. On the other hand energy meter chips are located in connection point and read the enrgy in kilowatthours  and also send the data to host PLC unit. This proposed detector system as two recorded energy data in host PLC unit, one which comes from the AMR-PLC,  and the other which comes from the PLC at the connection points. These two recorded energy data are compared in the host PLC; if there is any difference between two readings an error signal is generated. This means that there is an illegal electricity usage in the network. After that, the subscriber address and error signal are combined and sent to the central control unit. If it is, requested, a contacter may be included to the system at location to turn off the energy automatically, as in the case of illegal usage

14. CONCLUSION

            A detector system to determine illegal electricity usage via power line communication is designed and proposed. The proposed system is examined in laboratory conditions. Obtained results from this study show that if the AMR and detector system are used together, illegal usage of electricity may detected. The system functions with real-time monitoring users and burden forecast, which uses MV&LV PLC as its transmission media. The system is integrated with power management and burden control. Under power theft, the relay is switched off isolating the area of power theft from the EB side .LCD display also indicates power theft. Energy regulation does not represent an obstacle, since PLC service does not affect the power supply and maintains separate accounts from the core utility business. Once this proposed system is tried in real power lines, the distribution losses can be reduced effectively.

 REFERENCE

[1]   Hakki  Cavdar, ”A solution to remote detection of illegal electricity usage via power line communication”, IEEE Trans. Power Delivery,vol.19,no.4,Oct 2004.

[2]     T.Y.Lim and T.W.Chan, “Experimenting remote kilowatt hour meter through low voltage power lines at dense housing areas”, IEEE Trans. Power Delivery, vol.17, pp708-711,july 2002.

[3]     J.Newbury and W.Miller,” Multiprotocol routing for automatic remote using power line carrier systems”, IEEE Trans. Power delivery,vol.16 pp 1-5,Jan 2001.