Evaluation of Switching Over Voltages on High Voltage Circuit - ijcee

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y y KV y International Journal <strong>of</strong> Computer and Electrical Engineering, Vol.4, No.2, April 2012 to 1.17 times greater than normal operating phase voltage. 400 300 200 100 0 -100 -200 -300 -400 Advanced Graph Frame CB VOLTAGE ACROSS POLES PH:A PEAK 0.00 0.25 0.50 0.75 1.00 1.25 1.50 1.75 2.00 ... ... ... Fig. 6. Voltage across CB contacts in case.2. Case.3: Simulation <strong>of</strong> switching and reclosing <strong>of</strong> C.B., in presence <strong>of</strong> no-load transformer: In the third scenario system is in no load operating condition. Before starting the simulation these conditions are applied to the system: Transformers operate in no load condition and all <strong>of</strong> the 132kV outgoings are disconnected. Cables are disconnected from 132kV busbar. Circuit-breakers “=C02-QA1, =C02-QA2, =C01-QA1, =C01-QA2 and =C01-QA3” are closed and “=C02-QA3” is opened. Tap <strong>of</strong> the transformers are regulated on 1.05. In the moment <strong>of</strong> 0.999 seconds =C01-QA3 is opened and in the moment <strong>of</strong> 1.0653 seconds reclosed. Again in the moment <strong>of</strong> 2 seconds, the system becomes stable again. According to Fig. 7, the maximum peak over-voltage that occurs is about 428kV phase to earth equal to 1.86 times greater than normal operating phase voltage. 500 400 300 200 100 0 -100 -200 -300 -400 -500 Advanced Graph Frame CB VOLTAGE ACROSS POLES PH:C PEAK 0.00 0.25 0.50 0.75 1.00 1.25 1.50 1.75 2.00 ... ... ... Fig. 7. Voltage across CB contacts in case.3 Case.4: Simulation <strong>of</strong> switching, reclosing and reopening <strong>of</strong> C.B., in presence <strong>of</strong> no-load transformers and double circuit transmission line: In the forth scenario system is in no load operating condition. Before starting the simulation these conditions are applied to the system: Transformers operate in no load condition and all <strong>of</strong> the 132kV outgoings are disconnected. Cables are disconnected from 132kV busbar. Circuit-breakers “=C02-QA1, =C02-QA2, =C01-QA1 and =C01-QA2” are closed and “=C02-QA3 and =C01-QA3” are opened. Tap <strong>of</strong> the transformers are regulated on 1.05. In the moment <strong>of</strong> 0.999 seconds =C01-QA3 is closed and in the moment <strong>of</strong> 1.0653 seconds reopened. Again in the moment <strong>of</strong> 2 seconds, the system becomes stable again. According to Fig. 8, the maximum peak over-voltage that occurs is about 710kV phase to earth equal to 3.08 times greater than normal operating phase voltage. 800 600 400 200 0 -200 -400 -600 -800 Advanced Graph Frame CB VOLTAGE ACROSS POLES PH:A PEAK 0.00 0.25 0.50 0.75 1.00 1.25 1.50 1.75 2.00 ... ... ... Fig. 8. Voltage across CB contacts in case.4 Case.5: Simulation <strong>of</strong> switching, reclosing and reopening <strong>of</strong> C.B., in the presence <strong>of</strong> no-load transformers and single circuit transmission line: In the last scenario system is in no load operating condition. Before starting the simulation these conditions are applied to the system: Transformers operate in no load condition and all <strong>of</strong> the 132kV outgoings are disconnected. Cables are disconnected from 132kV busbar. Circuit-breakers “=C02-QA2 and =C01-QA2” are closed and “=C02-QA1, =C01-QA1, =C02-QA3 and =C01-QA3” are opened. Tap <strong>of</strong> the transformers are regulated on 1.05. In this scenario one circuit <strong>of</strong> the overhead line is disconnected from both upstream substation and “Fajr II S.S”. In the moment <strong>of</strong> 0.999 seconds =C01-QA3 is closed and in the moment <strong>of</strong> 1.0653 seconds reopened. Again in the moment <strong>of</strong> 2 seconds, the system becomes stable again. According to Fig. 9, the maximum peak over-voltage that occurs is about 750kV phase to earth equal to 3.26 times greater than normal operating phase voltage. 800 600 400 200 0 -200 -400 -600 -800 Advanced Graph Frame CB VOLTAGE ACROSS POLES PH:A PEAK 0.00 0.25 0.50 0.75 1.00 1.25 1.50 1.75 2.00 ... ... ... Fig. 9. Voltage across CB contacts in case.5 IV. CONCLUSION In this study, switching over voltages for 400kV circuitbreakers <strong>of</strong> the “Fajr II substation” have been analyzed. System components were modeled and implemented in PSCAD/EMTDC s<strong>of</strong>tware for further simulations. Five different case studies were defined and simulation has been done for each one. The voltage between two contacts <strong>of</strong> the middle breaker for three phases has been recorded. From above figures it can be concluded that there is some technical factors that can lower the switching over voltages. In this substation, the length <strong>of</strong> the transmission lines is the main reason. It can be observed from figures that the maximum probable switching over voltage that can occur is lower than maximum switching voltage withstood <strong>of</strong> the insulation <strong>of</strong> the 184
International Journal <strong>of</strong> Computer and Electrical Engineering, Vol.4, No.2, April 2012 circuit breaker. Based on this conclusion, there is no need for expensive shunt resistor or synchronizing switch for the 400kV circuit-breakers in the “Fajr II 400/132kV substation”. ACKNOWLEDGMENT The first author thanks Pr<strong>of</strong>. Rahimi for her valuable comments. The first author also thanks his wife, for her kindness during preparation <strong>of</strong> the paper. REFERENCES [1] A. F. B. Young, “Some Researches on Current Chopping in High-Voltage Circuit-Breaker,” in Proc. <strong>of</strong> IEE, Part II: Power Engineering, August 1953. [2] A. Greenwood, Electrical Transients in Power Systems, 2rd ed. John Wiley & Sons Inc, 1991, pp.93–97. [3] ABB Product information, 5409 722-101 en Rev.3, SWITCHSYNC F236, ABB Power Technologies AB, Dec 2005. [4] B. Sedaghat and M. Esmi, <strong>Switching</strong> over-voltage analysis for FajrII 400/132KV GIS S.S Report, Published only for client, Fajr Petrochemical Company, October 2009. [5] Introduction to PSCAD/EMTDC V4.1, Manitoba HVDC Research Center, Winnipeg, Canada, 2003. [6] J. R. Marti, “Accurate Modeling <strong>of</strong> Frequency Dependent Transmission Lines in Electromagnetic Transient Simulations,” IEEE Transactions on Power Apparatus and Aystems, PAS-101, Jan 1982. [7] V. Brandwajn, H. W. Dommel, and I. I. Dommel, “Matrix Representation <strong>of</strong> Three-Phase N-Winding Transformers for Stead-State and Transient Studies,” IEEE Transactions on Power Apparatus and Systems, PAS-101, June 1982. [8] F. Leon and A. Semlyen, “Complete Transformer Model for Electromagnetic Transients,” IEEE Transactions on Power Delivery, Vol.9, No.1, Jan 1994. [9] PSCAD/EMTDC Power System Simulation S<strong>of</strong>tware User's Manual, Manitoba HVDC Research Center, Winnipeg, Canada, 1996. Behzad Sedaghat was born in 1982 in Tehran, Iran. He received his B.Sc degree in power & energy engineering from Tehran Polytechnic University, Tehran, Iran in 2007 and his M.Sc in renewable energy engineering from Zanjan University, Zanjan, in 2010. He has three years experience in power & energy systems design as an Electrical Power Substations and DG Power Plants engineer in T.P. Hermod Company, Iran. He is now with Monenco Iran consulting engineers <strong>of</strong> MAPNA Group. He has written a book entitled “Power system analysis and protection systems with PSCAD/EMTDC s<strong>of</strong>tware” (Tehran, Tafresh University publications, 2007). His areas <strong>of</strong> research interest include: Energy & Power System, Power System Management, Planning and Reliability, Control and Integration <strong>of</strong> Renewable Energy Plants, Application <strong>of</strong> GIS in Power System Planning, and Electric Power System Dynamics. Mr. Sedaghat is a member <strong>of</strong> the Organization for Engineering Order <strong>of</strong> Building <strong>of</strong> Iran, Gold member <strong>of</strong> the Amirkabir University Alumni since 2007, member <strong>of</strong> the Zanjan University Superior Student Committee and member <strong>of</strong> the institute <strong>of</strong> electrical and electronics engineers (IEEE). He has received the “Superior Researcher Student Honor <strong>of</strong> Zanjan University” in 2009 and the “Electrical Department MS.c Superior Student” in Zanjan University in 2010. Majid Esmi was born on September 14, 1978. He received the B.Sc. degree in power engineering from Shahid Chamran University <strong>of</strong> Ahwaz, Ahwaz , Iran in 2000, and M.Sc. degree in power engineering from Sharif University <strong>of</strong> Technology , Tehran, Iran, in 2002. Currently, he is the scientific member in Azad University, Saveh branch, Saveh,Iran. 185
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