CHAPTER-3 ON-LINE MONITORING OF TRANSMISSION LINE USING GSM TECHNOLOGY

Transcription

1 37 CHAPTER-3 ON-LINE MONITORING OF TRANSMISSION LINE USING GSM TECHNOLOGY 3.1 INTRODUCTION Power sector is facing severe energy losses right from Generation to distribution, The technical losses in generation can be well defined and innovations are on to scale down these losses. The severe losses on account of Transmission and Distribution are indefinable but cannot be quantified with the sending end parameters. This illustrates the involvement of non-technical parameters in T&D of electrical energy. T & D losses are of greater concern for the Indian Electrical Industry (IEI) since their magnitude is huge when compared to other developed countries. The present T & D losses which include unaccounted energy loss are between 18 to 32% amounting to a financial loss of Rs 1,000,000 Cr PA. These losses are on account of improper handling of transmission and distribution system. If we can save even 1% out of the above losses it will be a definite help to the power sector in specific and the environment at large. As per The Energy and Resources Institute (TERI) [59], energy losses occur during the process of supplying electricity to consumers. The total T & D losses are combination of technical and non-technical losses. The technical losses are due to energy dissipated in the conductors and equipment used for transmission, transformation, sub-transmission and distribution of power. These losses are inherent in a system and can be reduced to a best level. The non-technical (commercial) losses are caused by pilferage, defective meters, and errors in meter reading and in estimating unmetered supply of energy.

2 38 Reduction of losses will have healthy economics and also a positive step to preserve environment, however it is often expensive and difficult to reduce technical losses. Replacement of old equipment with the latest is one way to reduce technical losses. The Life of system components can be increased substantially if the faults are sensed through an effective, speedy and highly sensitive wireless communication System. Current method being used to assess the damage on the transmission grid is by visual inspection. Due to dispersion of transmission lines over hundreds of miles, it is difficult to sense the fault by visual inspection or by using traditional methods. In order to acquire different parameters and deliver them to the control centers, it is required to install data acquisition systems (DAS) and various sensors in predetermined towers and communicate via wireless network. For efficient monitoring and control, a robust and fast communication system is required [60]. This chapter discusses how the different data is acquired and delivered to the control center for loss analysis and to initiate corrective measures by using different sensors and wireless communication. The proposed method is highly useful for the future deregulated power system and smart grid applications. There are many ways to collect the information i.e., SCADA, PLC, optical fiber, etc. However, it is impossible to use these systems in many places in the power system (remote places) and also costly. A wireless solution is thus sought. There are wide smart grid applications [41] using wireless communication. The GSM SMS and ZigBee communication are proposed [61] for monitoring over head conductors. The concept of using wireless sensors has proposed [62] for substation automation.the Y.Yang, F.Lambert and D.Divan were first proposed the use of sensor networks to monitor overhead transmission lines [63, 64]. R. A. Leon, V. Vittal, Y. Yang et al [65, 66] introduced the importance and implementation of sensors in power grid

3 39 monitoring. The proposed model consists of sensors like; voltage sensing transformer is used for acquiring change in voltage, Thermister for change in temperature and Accelerometer for cable sag & tilt due to overloading and climatic conditions. Wireless GSM is used to deliver and collect the data. Fig.3.1 shows the single line diagram of power system network using wireless communication. Fig.3.1. Single line diagram 3.2 LINEAR NETWORK MODEL This section explains the proposed linear network model. Fig.3.2 shows an example of long overhead transmission line where the number of towers in-between. The distance between two primary substations can be 50 kilometers. On the other hand distance between two towers can be 0.25 to 0.5 kilometer depending on actual needs and geographical constraints. To monitor the transmission line and acquire the changes in the power system line with respect to time, different sensors listed in Table 3.1 are used. In general all sensors are analog in nature and deliver output in the form of voltage, current, resistance, etc. All the signals will be fed for conversion to achieve signals which can be perfectly suitable for computing using state of art embedded technology.

4 40 Fig.3.2. Power system network with sensors The embedded technology collects data and converts it for soft computing. Appropriate software can compute these signals and creates control, information, data logging and communicating signals. The primary parameter which can change during all the conditions is voltage and it determines the energy loss. The change in voltage is directly proportional to losses to certain extent. The second parameter is current which gives information about real usage. Once, if the current goes high beyond the set limit, it creates sag (voltage sag) and power becomes infinite. So, entire thing will be considered as loss. Unless we have a proper tool to monitor, this cannot be identified and solved. A real relationship of usage verses loss can be arrived only from the magnitude of current. The change in temperature occurs on transmission line due to various reasons; it starts from simple overloading, continuous overloading, and climate changes. All this creates skin effect and makes them to elongate from its original length and thereby forms physical sag between two poles (Towers) [67, 68]. The proportional increment of cable length will increase I 2 R loss and voltage drops in the transmission lines.

5 41 To analyze the parameter called sag, created because of frequent change in temperature and it is essential to overcome on long term basis. Sag will not be created at the time of installation. During the course of time with the changes in temperature and climate sag will be created automatically and increase the loss. More sag can create tilting of transmission line during climatic turbulences. The effect of sag can be reduced by maintaining the temperature within the limit. The model is designed by considering voltage sensing transformers, accelerometers and temperature sensors. These are placed at 25% and 75% of the total distance and close to the poles/towers. Each sensor sends data at regular intervals [65]. Data acquisition system also placed on the poles / towers to collect the data from the sensors. The data obtained on transmission lines are sent through GSM lines to the control centre in the substation. At the receiving point (control centre) all GSM data will be received from various parts of transmission line and fed to a single computer. Analysis is made regarding the losses at various points and will be displayed. All the collected data will be logged safely for future or present comparison of utilization factor (UF). The UF based demand management will reduce various burdens on transmission line and keeps devices perfect. The proposed scheme presents data like power handled by tower, losses between tower to tower, loss percentages at each tower, overall efficiency of transmission line. As a decision making system, the scheme will deliver control outputs in the form of digital and will be converted into RS-232 standard. The RS-232 data will be converted into GSM signals and passed to distribution end. Thus, wireless communication provides a major contribution to reliable network operation and efficient energy management.

6 42 Table 3.1.Types of sensors for monitoring Monitoring parameters Cable tilt Inclination Temperature Extension & Strain Cable position Current Magnetic field Power Quality Graph Type of sensor Accelerometers Accelerometers Temperature sensor Strain sensor Accelerometers Magnetic field Sensors Magnetic field Sensors Magnetic field Sensors 3.3. STRUCTURE OF LABORATORY MODEL The structure of the proposed laboratory model for on-line analysis of transmission line is shown in Fig.3.3. The model is a scaled down version of the original system using low voltages. The change in voltage, current, temperature and angle are scale down values of real variables. The same circuits can be employed for higher version installation at the field areas. There are no changes required except enclosures for the DAS circuit. The proposed technology consists of the following seven major categories to meet on-line challenges and acquiring transmission line data: Instrument Transformers Signal conditioning circuits (SC) Accelerometers Temperature Sensors Embedded microcontroller (EMC) Software required Communication network

7 43 Fig.3.3.Block diagram representation of the laboratory model Instrument Transformers Instrument transformers are used in the measurement and control of alternating current circuits [10]. These are essential to step down the high voltage / current into measurable low voltage / current for measuring purpose. Isolation with ratio metric reduction will be done by these types of transformers. There are two distinct classes of instrument transformers: (1) Potential transformer (2) Current transformer Potential Transformers The potential transformer operates on the same principle as that of a power or distribution transformer. The main difference is that the capacity of a potential transformer has ratings from 100 to 500 volt amperes (VA). The low voltage side is usually wound for 110 V. The high voltage primary winding of a PT has the same voltage rating as that of the primary circuit. Assume that it is necessary to measure the voltage of a 3.3kV, single phase line. The primary of the PT is rated at 3.3kV and the

8 44 low voltage secondary is rated at 110V. The ratio between the primary and the secondary winding is: 3300/110 or 30/1. Current Transformers Current transformers are used so that ammeters and the current coils of other instruments and relays need not be connected directly to high voltage lines. In other words, these instruments and relays are isolated from high voltages. CTs also step down the current in a known ratio. The use of CT allows using relatively small and accurate instruments, relays and control devices of standardized design in the measuring circuits. The existing transmission line need not be modified or reconfigured, because the CT is noncontact primary (Clamp type or tong type) type. The secondary winding has the standard current rating of 5A; therefore the ratio between the primary and secondary current is xxx/5a Signal Conditioners These devices are made up of semiconductor operational amplifiers. Signal conditioners are more reliable. The output of secondary isolation system will be AC in nature, must be rectified, conditioned and calibrated as per the requirement of conversion circuits. These circuits are Op-Amp based full wave precision rectifiers (or) absolute rectifiers. These circuits meet overall standards of measurements. The prime objectives of these devices are to rectify, filter, setting up the calibration limits, protecting the high voltage hazards, protecting the inputs and outputs. Output of these circuits will be pure DC in nature Voltage Sensing Voltage sensing circuit is shown in Fig.3.4. It consists of bridge rectifier; it can be used to convert AC to DC. A1 is an inverting unity gain amplifier. A2 is

9 45 inverting summing mixed gain amplifier. During positive half cycle the Op-Amp A1 produces an output of 0.454V. Op-Amp A2 produces an output of 0.908V across the path having gain of 2 and an output of 0.454V across the path having a gain of 1. Thus, the resultant output voltage is 0.454V. It can be amplified to require voltage by varying the trim pot. The 500K trim pot is adjusted so that a full scale output voltage of 5V is produced. A capacitor is connected to A2 so that it acts as an integrator. Hence output voltage is a pure DC voltage it is then given to ADC. Fig.3.4 Voltage sensing circuit diagram Current Sensing Current sensing circuit diagram is shown in Fig.3.5. Current sensing is very similar to the voltage sensing, instead of potential divider a shunt to be used to convert current into voltage. Once current is converted into voltage, Full wave precision rectifier (FWPR) can be directly used and output will be 0-5V corresponding to the minimum to maximum CT value of 0-5Amps.

10 46 Fig.3.5 current sensing circuit diagram MEMS Accelerometer MEMS Technology is a well known abbreviation for Microelectromechanical systems even though; there exist various names for MEMS technology such as micro machines etc. MEMS Accelerometer accurately detects and measures acceleration, tilt, shock and vibration in performance-driven applications. In industry it detects the power, noise, bandwidth and temperature specifications and earthquake detection in geotechnical engineering (Bernstein, 1999). Since there are various types of sensors for various applications, there is a need to select the right sensors which fit to the intended applications. In our work we have used MEMS Accelerometer to measure transmission line tilt and sag. We have used three axes MEMS accelerometer which provide voltage output for the change in X, Y, Z axes. No need to connect signal conditioner because it produces 0 to 5V for the change in physical directional changes Temperature Sensors Transmission lines are heated due to over load and climatic conditions. When line current increases, the conductor heats up, elongates, and the line sag increase. If the line is operated beyond its maximum design temperature, the line sags may violate

11 47 design clearances. Use of the Transmission Line Monitoring System for dynamic ratings allows utilities and transmission operators to develop and apply line ratings in real time, based on actual weather conditions instead of fixed, conservative assumptions. By using temperature sensors and wireless communication, over-head lines and cables are monitored, analyzed, and visualized with one system. In the proposed model Thermister is used as a temperature sensor which is inexpensive, easy to use and adaptable. Temperature is the most important parameter during high current flow on the cables, possibility of losses will be very high and can be detected using temperature sensor and appropriate tripping action can be performed to save energy Embedded Microcontroller Generally A/D converters are interfaced with the microprocessor using a separate interfacing IC namely programmable peripheral device. This requires large hardware circuit. But in the proposed design, state of art embedded system technology is used to reduce lot of hardware. These devices consist of packed hardware inside; any devices can be brought down to the front end and can be used. Output from signal conditioning circuits is connected to this circuit for A/D application. Simultaneously all analog data are fed and digitized data are sent to computer as RS-232 signals. The digitized data is to be decoded for real values. The expected speed of this device is 9600 baud rate. It proposes middle end embedded microcontroller like pic16f877a, which consists of 8 channel 10bit ADC with lots of additional features. These devices require very minimum supporting hardware s like clock and reset circuits externally. The embedded circuit diagram is shown in Fig.3.6. The circuit consists of 1) Power supply 2) Clock circuit

12 48 3) PIC16F877A 4) Reset circuit 5) RS232 circuit Fig.3.6 Embedded circuit diagram Power Supply Circuit Irrespective of the technological growth one must construct a reliable power source for embedded controller. A 230V/12V step down transformer and bridge rectifiers are used to convert into DC. A constant voltage regulator LM7805 with necessary filters is used to produce constant 5V given to embedded circuit. Irrespective of the change in voltage and current, output voltage will be kept constant at 5V.

13 Clock Circuit 10 MHz crystal as a resonator made up of Quartz is used in this work to meet the requirements. Generally crystal oscillator is made up of quartz whose crystalline structure will not be changed under any circumstances on physical changes. 10 MHz crystal oscillator is used to produce constant frequency. Further, it can be divided inside the microcontroller as per the requirement of the operation to achieve exact timing. The general disadvantage of the crystal, it may produce abnormal clocking at some conditions, which can be eliminated using appropriate low pass filter coupled across crystal and connected to ground. Crystal is connected across 13 and 14 pins PIC16F877A Microcontroller Microprocessors brought the concept of programmable devices and made many applications of intelligent equipment. Most applications which don t need large amount of data and program are tended to be costly and consist of a lot of peripherals. These drawbacks lead to the use of microcontroller, which is a true computer on a chip. This is heart of the work, which collects the data, passes to the computer and takes control action. To perform various operations and conversions required to switch, control and monitor the devices a processor is needed. In this research a PIC16F877A Microcontroller is used. The pin-diagram of the Microcontroller is shown in Fig.3.7. The features and external requirements are discussed below. Features High-performance RISC (Reduced Instruction Set Controller) CPU Only 35 single word instructions to learn All single cycle instructions except for program branches which are two cycle Operating speed: DC - 20 MHz clock input and DC ns instruction cycle 4K x 14 words of Program Memory (EPROM)

14 x 8 bytes of Data Memory (RAM) Interrupt capability (up to 14 internal/external interrupt sources) Eight level deep hardware stack Direct, indirect, and relative addressing modes 12-bit multi-channel Analog-to-Digital converter On-chip absolute band gap voltage reference generator Universal Synchronous Asynchronous Receiver Transmitter, supports high/low speeds and 9-bit address mode (USART/SCI) Industrial Features Built in ADC of multi channel with 10 bit accuracy- used to acquire voltage, current, temperature, power. Built in reference facility and external reference provision- to fix a bandwidth of reference voltage. Built - in ports-to drive the relays and getting feedback from the relays. Requirements of PIC16F877A A separate power supply for digital and analog supplies must be provided to prevent affecting the quality of analog measurement due to digital current fluctuations. Double regulated completely filtered analog reference supply. Needs external power on reset and CPU synchronization switch. External quartz crystal to be used for frequency stability. 10 MHz for 9600 baud rate 20 MHz for baud rate RS-232 converter is used to link it with the computer. For all the analog inputs voltage should not exceed 5V.

15 51 For digital outputs we should not consume current beyond 25mA. All the logical inputs must reach PIC16F877A as a perfect square wave form. Software Advantages Reduced Instruction set computing RISC orientation. Only 35 single word instructions to learn. Reduces design and learning time. RS-232 interface is possible for COMPORT serial port. This embedded can be interfaced with all old and latest computing languages. Basic, C, VB. Host CPU can be varieties of operating frequency as well as different bits. Pin Diagram Fig.3.7 Pin Diagram of PIC16F877A Reset Circuit In Fig.3.6 the capacitor C1 is in the OFF condition when power is switched OFF. When the power is switched ON or Reset then this capacitor gets charged through the resistor R2 and then through R1 this appears at the MCLR pin of the PIC. This is the memory clear pin and thus the memory is cleared and is ready for use as

16 52 soon as power is switched ON. S1 is the synchronous switch which is also used for the same operation and for PC and PIC synchronous operation RS-232 In personal computer, data transfer takes place serially. RS-232 standard is used for serial communication. PIC Microcontroller is linked to PC through the RS- 232 port. The most common communication interface for short distance is RS-232. RS-232 defines a serial communication for one device to one computer communication port, with speeds up to 19,200 baud. Typically 7 or 8 bit (on/off) signal is transmitted to represent a character or digit. The 9-pin connector with pin detail is shown in Fig.3.8. Fig.3.8 RS-232 Pin connector Interface Analog values like voltage, current, temperature, etc will be connected on port A and E. Digital output like relays and input like switch gear positions can be connected to digital port like port B,C,D. Port C upper two lines is used as TXD and RXD for serial communications. The process will be started as soon as the EMC is powered and acquires the data for display, control and for data logging. The general electrical data like voltage, current, frequency is more traditional than new sensor devices like accelerometer and temperature sensors on transmission

17 53 line. The concept of all electrical and non electrical parameter processing will be done using Op-Amp based electronic circuits. Output of the signal conditioner will be fed to EMC for analog to digital conversion, digital to serial. EMC device has lot of built in features like A/D, USART, RAM, EEPROM etc. The most important concept of programming is more essential i.e, current conversion takes more than 70% of time and rest goes to all other parameters, because, current is the most crucial parameter in decision making on substations/grids. The conversion ratio is to be altered as per the priority of measurement. The Table 3.2 shows 85% of time is allocated for current sensing because it is most fluctuating parameter of the transmission line and rest goes to all other parameters. Non-electrical parameters will not change offen, so acquiring them doesn t solve any problem. So least priority given to acquire non electrical parameters. Table 3.2: Conversion ratio for different parameters Parameter % of Time Conversion Ratio (% of Time*9600bd) Current Voltage Sag Temperature The analog input given to MUX inside the EMC and selects as per the priority given in Table 3.3. MUX accepts many analog data and sends one at a time to ADC as per the control inputs given to it. MUX must be analog MUX, and output of the MUX must be connected to 10 bit ADC which is a built in option of EMC. The conversion rate is very high, and given data will be fractioned to The converted

18 54 analog data and MUX input data combinely can represent digital equivalent of the concern input. Table 3.3:Chanel selection MUX input ADC output Channel Ch 0 5V Ch 1 2.5V Ch 7 2.5V The Table 3.3. shows, how the multiple inputs enters to the EMC and works. The above data must be decoded to get real value. The data of the ADC will be stored on to the RAM for short time and fed to USART (or) UART (Universal Synchronous Asynchronous Receiver Transmitter). USART is device, converts parallel data into serial data and serial into parallel and works in synchronous with the counter part of CPU. It works at a speed of 9600 baud rate, without this networking is absolutely not possible. Even higher baud rate could be achieved for very high speed applications. Output of the USART will be fed to GSM transmitter. In the substation, GSM receives data from different GSM transmitters at different locations and deployed in the control centre PC for further analysis and future comparison Communication Network To transmit on-line acquired data to substations, wireless communication is the most advanced and cost-effective in terms of the equipment, installation cost and installation time [11]. Communication standards are categorized based on their communication range, maximum throughput, power consumption, etc. Larger the communication range, lower the maximum throughput and larger the power

19 55 consumption. For long distance transmission a dedicated channel is required. Most devices are onsite equipments used to acquire the data at one end supports to communication equipments and passed through leased lines, often the quality of communication is kept under leased line owners. The leased lines are not dedicated to one single application. Decoding the necessary data is much complex because of many servers were introduced in between and causes slow down the data transfer rate. There are many communication techniques like Unidirectional RF, carrier communication, ZigBee, GSM, Internet, CDMA, Blue tooth, Fiber-optic cable, Bidirectional RF, etc. Out of which many of the communication systems are leased lines and dependency goes to service providers. Few of them are suitable for long distance communication. Now a days carrier power line communication and Supervisory Control and Data Acquiring Systems are the powerful methods widely used for transmission lines. But these methods have some drawbacks. Whenever there is disconnection between two ends of the transmission line, the communication can t be possible, which leads to reduction of utility factor & energy loss. For remotelylocated transmission lines, PLC & SCADA connection cannot found benefit. Therefore, wireless GSM is best suitable for online data acquisition of long and remote lines GSM Technology GSM (Global System for Mobile Communications) was developed in Popular cellular phone operates in India use GSM or the CDMA technology to provide voice and data services. GSM uses a combination of TDMA (time division multiplexing) and FDMA (frequency division multiplexing). This means that users A and B are not only sharing the channel in time but also frequency. This means that user A is ON the channel 890MHz for 2 seconds, then jumps to 900Mhz channel for

20 56 the next two seconds, then jumps to 910MHz for the next 2 seconds and so on. Thus, each user uses a different frequency at different time slots. This is called Frequency Hopping. There is GSM 900, 1200, 1800, 2100etc these days. 900 is the operational frequency of the GSM in MHz. The key characteristic of a cellular network is the ability to re-use frequencies to increase both coverage and capacity. The re-use distance, D is calculated by using equation 3.1. D = R 3N 3.1 Where R is the cell radius and N is the number of cells per cluster. Cells may vary in radius in the ranges (1 km to 30 km). Cell Coverage comparison of different frequencies are given in Table 3.4. The boundaries of the cells can also overlap between adjacent cells; large cells can be divided into smaller cells. Table.3.4: Coverage comparison of different frequencies Frequency (MHz) Cell Radius (km) Cell Area (km 2 ) Relative Cell RESULT ANALYSIS The Results for different faults created on transmission line for the analysis purpose are shown in Fig.3.9. The results shown in Fig.3.10 are the real-time data received from different GSM receivers at different places of transmission line. This data sheet consists of date, time, GSM transmitter code, voltages of all phases, cable tilt angle and temperature of the cable.

21 57 Fig.3.9 (a) Normal condition Fig.3.9(a) shows results at normal condition (without fault). At this condition all phase currents and voltages are almost equal. There is no loss and the data obtained on real time shows perfect working of the system. Fig. 3.9 (b) Single line to ground fault The currents and voltages in Fig.3.9(b) shows that, there is a single line to ground fault in R-phase. Abnormal rise in current make voltage falling and finally collapses the grid. The design is not for tripping the relays during switching

22 58 conditions of the circuit breaker because overloads are possible during instantaneous switching of circuit breaker. If the fault retains for more than two and half-cycles the trip command will be fed to the relays thereby huge power can be saved during abnormalities. The circuit consists of sensing system with fast acting relay to trip the circuit breaker and to avoid losses during short circuit. The tripping graph is shown in the next chapter. Fig.3.10(a) normal condition The results shown in Fig.3.10(a) are the real-time on-line data obtained from GSM transmitters at 25% and 75% of the total distance at normal condition. Initially the values for all phases are considered to have voltage 48v, line tilt angle is 90 and temperature is 30 c. Results of Fig.3.10 (b) gives change in voltage levels in Y-phase due to fault, other phase voltages, tilt angle and temperature sent by GSM transmitter placed at

23 59 25% of the total line distance. During this condition an automated command will be sent by the EMC to trip the circuit breaker and save energy with in shortest time period may be four cycles. Fig.3.10 (b) Fault at 25% of distance Results of Fig.3.10 (c) gives change in voltage levels in Y-phase due to fault, other phase voltages, tilt angle and temperature sent by GSM transmitter placed at 75% of the total line distance. During this condition an automated command will be sent by the EMC to trip the circuit breaker and save the energy with in shortest time period may be four cycles. Fig.3.10 (c) Fault at 75% of distance Fig.3.10(d) shows the change in cable tilt and temperature sent by GSM transmitters at 25% and 75% of the total line distance. These are the non-electrical

24 60 parameters obtained through GSM from the field and will be used to take effective decision. This will be useful to the engineers to take preventive steps (includes the safety tripping to save energy from thermal effects, and cable elongation due to over load and climate) to avoid damage to the cables. Based on these results partial load shedding or load diversion should be effected to save power. Fig.3.10 (d). Temperature & cable sag angle at 25% and 75% 3.5 HARDWARE FIGURES Photographs of hardware models are shown in Fig Fig.3.11(a) Sending end model

25 61 Fig.3.11(b) Receiving end model Fig.3.11(C) Transmission line

26 62 Fig.3.11 (d) Resistive load Fig.3.11 (e) Fault sensing at 25% of total distance

27 63 Fig.3.11 (f) Temperature sensor Fig.3.11 (g) Accelerometer

28 64 Fig.3.11 (h) Receiving centre 3.6. CASE STUDY Line diagram of 220/132/33kV substation Renigunta, Chittor district, Andhra Pradesh, India is shown in Fig It consists of 6 numbers of 220kV, 13 numbers of 132 kv and 7 numbers 3kV feeders. The loss analyses of each, 220kV feeder is carried out for two periods i.e. one month & one year and is tabulated in Tables 3.5 and 3.6 respectively. The graphical representation of percentage losses are shown in Fig.3.13.

29 65 AREA OF THE SS :20.18Acres SURVEY NO: 29-1A:29-2:30-1 DATE OF CHARGING :1961/1971/1980/1982/1995 CAPACITY: (3 X 100 MVA)+(31.5+2X16)MVA REACTIVE POWER COMPESATION:(1X 7.2+2X5) MVAR BATTTERIES: 200 AH AMARA RAJA (M.F) BATTERY CHARGER: DUBAS& HEE 220/132/33 KV SS RENIGUNTA SRIKALAHASTI C.K.PALLI KODURU MANUBOLU - II MANUBOLU - I BUS COUPLER SIEMENS 3 AP 1 FG IND/07/3848 ALSTOM FXT 14F ALSTOM FXT 14F ALSTOM FXT 14F ABB ELF SL-4-1 IB ALSTOM FXT 14F KV/110V BUS II - PT BUS - II BUS - I CGL 200-SFM ALSTOM FXT 14F ABB ELF SL-4-1 IB KV/110V BUS I - PT ABB ELF SL-4-1 IB ALSTOM FXT 14F PTR III 100 MVA CGL BH-8849/2 PTR I 100 MVA CGL T -8449/2 PTR II 100 MVA CGL T /5 ALSTOM FXT 14F BHEL 3ARS ABB ELF - SF 2-1 IB CONTROL ROOM GRINDWELL NORTON CGL 120 SFM - 32 B C M.MAGALAM I M.MAGALAM II AMARARAJA SIEMENS 3 AP 1 FG IND/05/ KV/110V BUS PT - I STN. TRANS. - II 33KV/440V 100 KVA YERPEDU BHEL HLD 2/ KV/110V BUS PT - II RAILWAYS - I GAJULAMANDYAM - II BHEL HLD 2/ RAILWAYS - II GAJULAMANDYAM - I PUTTUR -II BHEL 3ARI EG PTR III 16 MVA NGEF LANCO PUTTUR -I CGL 120 SFM - 32 B C CGL 120 SFM - 32 B C PTR II 16 MVA NGEF SIEMENS 3AF SN/68 TIRUPATHI SIEMENS 3 AP 1 FG IND/05/1290 ALSTOM FX PTR I 31.5 MVA APEX T - 371/45329 SIEMENS 3AF S/1960 THUKIVAKAM - I CHANDRAGIRI -II ABB ELF SL ABB ELF SL CAP..BANK - III 5 MVAR BHEL 110 KVAR THUKIVAKAM - II CHANDRAGIRI -I CAP..BANK - II 5 MVAR BHEL 110 KVAR CAP..BANK - I 7.2 MVAR BHEL/SHREEM 200 KVAR KARAKAMBADI 33KV/110V PT LA INDEX PO WER TRANSFO RMER CVT AUTO TRANSFO RMER ISO LATOR STN. TRANSFO RMER STN. TRANS. - I 33KV/440V 100 KVA C.T BREAKER CAP. BANK 220 KV Fig Line diagram of 220/132/33KV substation Renigunta P.T 132 KV 33 KV

30 66 Table 3.5: 220kV feeder wise loss calculations for the month of Jan 2011 in O S D of Renigunta S. No Name of the Feeder Loss( kw) % Loss 1 Manubolu-I Manubolu-II Mahadeva Mangalam-I Mahadeva Mangalam-II C.K.Palli Kodur Table 3.6: 220kv feeder wise loss calculations from Jan 2011 to Dec 2011 in O S D of Renigunta S.No Name of the Feeder Loss(KW) %Loss 1 Manubolu-I Manubolu-II Mahadeva Mangalam-I Mahadeva Mangalam-II C.K.Palli Kodur Total Feeder line losses are calculated by using the equation 3.2 and percentage of line losses are calculated by the equation 3.3. Sample calculations of feeder loss: L i n e l o s s e s ( E 1 I 2 ) ( E 2 I 1) = = ( ) ( ) = kW ( E 1 I ) + 2 ( E 2 I 1) P e r c e n ta g e o flin e lo s s e s ( E + 1 E 2 ) = % 3.3

31 67 = ( ) ) % = 0.35% Where E 1 = Sending end export units E 2 = Receiving end export units I 1 = Sending end import units I 2 = Receiving end import units Fig Loss analysis of the feeders 3.7. CONCLUSIONS A laboratory model of the transmission line on-line monitoring and real-time data acquisition by deploying sensors is developed and its operation is demonstrated. They acquire the required data and transmit it to the control centre by using wireless GSM communication. In the control centre, analysis is made and corrective action to be taken will be advised for maintaining the UF and reducing the energy losses. Case study of Renigunta substation is considered. The loss analysis for 220kV feeder has

32 68 been carried out for a period of one month and also for one year. By observation it is clear that, losses are high. With the effort detailed above, if we can reduce even a small amount of these losses, we will be saving huge natural resources and money. Conserving natural resources will be a big boost in conservation of environment. Sensors and Wireless GSM communication is suggested for on-line monitoring and reducing energy loss. The wireless communication network offers advantages over conventional techniques such as faster response, lower cost, always connected and two-way communication.