1. By: Mohan K M, Ganesh C, Yerriswamy A Microcontroller Based Mho Relay Under the guidance of Mrs. Jyothi T N

2. INTRODUCTION 6/23/2014Dept. EEE PESIT 3. 6/23/2014Dept. EEE PESIT 4. POWER SYSTEM PROTECTION Main idea of protection is to remove faults as quickly as possible mean while maintains the system stability. Under abnormal operating conditions protection is necessary for Safety of electrical equipments. Safety of human personnel. Sequence of events in relation with a fault 1. Fault occurrence 2. Sensing of fault 3. Isolation of faulted section Unit Generator-Tx zone Bus zone Line zone Bus zone Transformer zone Transformer zone Bus zone Genera tor ~ XFMR Bus Line Bus XFMR Bus Mot or Motor zone 6/23/2014Dept. EEE PESIT 5. Primary protection Backup protection Classification of relays based on application 1. Under voltage, under current & under power relays 2. Over voltage, over current & over power relays 3. Directional or reverse current relay 4. Differential relay 5. Distance relay TYPES OF PROTECTION 6/23/2014Dept. EEE PESIT 6. Distance relay 1. Impedance relay 2. Mho relay 3. Reactance relay Mho relay is a distance relay with inherent directional element. 6/23/2014Dept. EEE PESIT 7. It has 3 zones of protections 1. Zone 1: 80-85% of protected line 2. Zone 2(minimum): 120% of protected line Zone 2(maximum): < protected line + 50% of shortest second line 3. Zone 3F: 1.2(protected line + longest second line) Zone 3R: 20% of protected line MHO RELAY 6/23/2014Dept. EEE PESIT 8. Zone 1 Zone 2 Zone 3 6/23/2014Dept. EEE PESIT ZseenI1 Z1Iseen>I2 Z2setIseen>I3 Relay 9. Zone 1: Instantaneous Zone 2: 0.5 sec Zone 3: 1 sec TRIPPING TIME 6/23/2014Dept. EEE PESIT 10. BLOCK DIAGRAM VOLTAGE INPUT CURRENT INPUT ZERO CROSSING DETECTOR MICROCONTROLLER KEYPAD CONTACT LCD ANALOG TO DIGITAL CONVERTER VOLTAGE INPUT CURRENT INPUT 6/23/2014Dept. EEE PESIT 11. Current sensor is used to get corresponding voltage output and wave respectively. The output wave is sampled using ADC. From the repetitive measurement calibration of digital samples into corresponding current magnitude is achieved. 6/23/2014Dept. EEE PESIT 12. High voltage is converted into low voltage by step down transformer. Analog voltage converted into Digital by ADC. Voltage magnitude is found by sampled digital value. 6/23/2014Dept. EEE PESIT 13. Multisim 13 MATLAB 2013Proteus 8 6/23/2014Dept. EEE PESIT 14. CURRENT AND VOLTAGE MEASUREMENT CIRCUIT Current Measurement circuit Voltage Measurement circuit 6/23/2014Dept. EEE PESIT 15. OUTPUT OF MEASUREMENT CIRCUIT Current Measurement circuit output Voltage Measurement circuit output 6/23/2014Dept. EEE PESIT 16. Curve fitting to make current measurement Accurate 6/23/2014Dept. EEE PESIT 17. Current Measurement Current in Microcontroller Current by Ammeter -0.441 0 -0.361 0.25 -0.291 0.43 0.071 0.82 0.4471 1.22 0.877 1.62 1.3871 2.1 1.96 2.57 2.5471 3.13 3.3471 3.86 3.7871 4.23 4.3671 4.82 4.9471 5.3 6.0371 6.25 6.9071 7.05 8.6471 8.75 10.461 10.45 12.421 12.47 13.651 13.87 14.671 15.05 After Curve Fitting 0.0717 0.2235 0.3454 0.8523 1.2446 1.6257 2.0633 2.5758 3.1222 3.8677 4.2670 4.7799 5.2845 6.2455 7.0451 8.6553 10.0992 11.1802 11.2752 10.6593 6/23/2014Dept. EEE PESIT 18. DESIGNING OF MAIN POWER CIRCUIT 6/23/2014Dept. EEE PESIT 19. DESIGNING TOOLS Auto CAD 2010 SOLID EDGE 18 6/23/2014Dept. EEE PESIT 20. MODEL DESIGNED IN SOLID EDGE 6/23/2014Dept. EEE PESIT 21. 6/23/2014Dept. EEE PESIT 22. ADVANTAGES OF MICROCONTROLLER BASED RELAY 1. Flexibility 2. High reliability 3. Fast operation 6/23/2014Dept. EEE PESIT 23. CONCLUSION From the observed performance of several tested cases, it can be seen that the model works satisfactorily and gives excellent results. Many tests have been conducted successfully. These relays are compact, reliable and flexible over conventional relays. The relay algorithm computation speed is increased and accuracy is not compromised. The relay also provides improved performance and user friendly human interface. 6/23/2014Dept. EEE PESIT 24. REFERENCE [1] Power system engineering by R.K Rajput page no 912 to 946. [2] Text book on power system engineering by A.chakrabarthi, M L Soni, P V Gupta, U S Bhatnagar, revised edition, Dhanpat Rai publishers [3] Power system protection and switchgear by Bhuvanesh A Oza, Nirmal kumar C Nair,Rashesh P Mehta,Vijay H Makwana [4] IEEE Tutorial Course, Microprocessor Relays and Protection Systems. The Institute of Electrical and Electronics Engineers,INC., 1987 [5] IEEE Tutorial Course, Computer Relaying, The Institute of Electrical and Electronics Engineers, INC., 1979. [6] V. Gurevich, Electric Relays Principles and Applications, Taylor & Francis Group, LLC, 2006. [7] K. M. Silva, W. L. A. Neves and B. A. Souza, "EMTP Applied to Evaluate Three- Terminal Line Distance Protection Schemes," International Conference in Power System Transients (IPST'07) in Lyon, France, pp. 1-6, June 4-7, 2007. 6/23/2014Dept. EEE PESIT 25. 6/23/2014Dept. EEE PESIT Ganesh C Yerriswamy A Mohan K M