• The Transactions of the Korean Institute of Electrical Engineers A
• /
• v.52 no.12
• /
• pp.713-721
• /
• 2003

This paper analyzes the switching overvoltage occurred on 345kV underground power cable system as well as combined transmission system using EMTP. Cable length and closing time, preinsertion resistance have effect on switching overvoltage. Therefore, this paper analyzes the switching overvoltage occurred on conductor and sheath with change of those parameters. Specially, the cross bonding position becomes discontinuity point because of the difference between surge impedance of metal sheath and that of lead cable. Thus, the transmission and the reflection of traveling wave complexly occur at this connection point. According to these influences, voltage between sheath and earth as well as voltage between joint boxes rise. Time to crest point of switching overvoltage is longer than lightning overvoltage. Even though the voltage induced by switching surge is smaller than lightning surge, that voltage may have serious effect on the metal sheath. Therefore, this paper also analyses the reduction effect of switching overvoltage when the preinsertion resistance of circuit breaker is considered.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.63 no.6
• /
• pp.764-769
• /
• 2014

This paper describes sheath voltage limiter(SVL) transient characteristics by switching overvoltage considering single point bonding in underground transmission cables. The crossbonding system is generally used for grounding methods of underground transmission system. However, the single point bonding system is used in selective area which is difficult to consist of crossbonding major section. The sheath voltage limiters are connected between joints in the single point bonding. Specially, the high overvoltage might be generated in that section as well as the aging of sheath voltage limiter might be progressed by various electrical stress including lightning overvoltage, switching overvoltage and power frequency overvoltage. Therefore, in this paper, the switching overvoltage characteristics in underground cables are firstly analysed using EMTP simulation. Then, the switching overvoltage of sheath voltage limiter is also studied in single point bonding. Finally, the reduction method of sheath voltage limiter switching overvoltage is proposed by various simulation studies including circuit breaker operating order.

• Proceedings of the KIEE Conference
• /
• 2002.07a
• /
• pp.481-483
• /
• 2002

In this paper, for continuously changed closing time of circuit breakers, switching overvoltage on 345kV underground transmission systems are variously analyzed using EMTP with statistical analysis method. And, switching overvoltage and closing surge occurred in conductors at sending and receiving end and metal sheath with variation of cable length are analyzed, and the reduction effects for switching overvoltage considered preinsertion resistance of circuit breakers are examined.

• Proceedings of the KIPE Conference
• /
• 1998.07a
• /
• pp.323-327
• /
• 1998

Under high power IGBTs Switching, a large overvoltage is induced across the IGBT module due to the stray inductance in the circuit. This paper proposes a new gate drive circuit for high power IGBTs which can actively suppress the overvoltage across the driven IGBT at turn-off while preserving the most simple and reliable power circuit. The turn-off driving scheme has adaptive feature to the amplitude of collector current, so that the overvoltage can be limited much effectively at the fault collector current. Experimental results under various normal and fault conditions prove the effectiveness of the proposed.

• Proceedings of the KIEE Conference
• /
• 2005.07a
• /
• pp.644-646
• /
• 2005

The air clearance of the transmission tower is determined by the switching overvoltage of the system, and the insulator length is determined by contamination design. This paper described the switching overvoltage analysis result of 500 kV system and air clearance design. The overvoltage include fault initiation, fault clearing, closing and reclosing overvoltages. We illustrated the contamination design example, air clearance design of a tower considering swing angle of the conductor.

• Proceedings of the KIEE Conference
• /
• 2008.07a
• /
• pp.442-443
• /
• 2008

This paper describes modeling using the EMTP/ATPDraw for reclosing analysis in 154kV combined transmission systems, and analyzes switching overvoltage. Current transformer established at lead-in area and lead-out area in transmission line and circuit breaker were modeled using TACS in the EMTP/ATPDraw. And also MODELS was constructed by signal processing of the operating reclosing. The simulation was carried out the switching overvoltage according to the length of overhead and underground transmission line, overvoltage between sheath and earth, and voltage between joint boxes.

• Proceedings of the KIEE Conference
• /
• 1990.11a
• /
• pp.166-169
• /
• 1990

The purpose of the circuit breaker on power system is to disconnect the faulty part from the system and to maintain the integrity of the system. With switching overvoltages are generated. When the system voltages become higher, switching overvoltage is important factor in insulation co-ordination. Since the no-load reclosing overvoltage with inductive source is severe, this paper deals with the reclosing overvoltage and the effect of closing resistor. This reclosing overvoltage of 27-bus model system with and without closing resistor is analyzed by using EMTP (Electro-Magnetic Transients Program) for both deterministic and Stochastic model.

• Proceedings of the KIEE Conference
• /
• 2005.11b
• /
• pp.280-282
• /
• 2005

This paper describes switching overvoltage generated during transient state in 22.9kV combined distribution systems. For analysis, distribution overhead line, underground cable and surge arrester are modeled using EMTP/ATPDraw. Simulation results show switching overvoltage according to various kind of parameter and systems such as closing angle and cable length.

• Proceedings of the KIEE Conference
• /
• 2008.11a
• /
• pp.391-393
• /
• 2008

This paper is analysed by switching overvoltage on operating reclosing in 154 [kV] combined transmission systems. Combined transmission systems are modeled by EMTP/ATPDraw program. It is fault condition that simulate high resistance earth fault. The simulation is carried out considering variation of parameters such as resistance value of fault point and rate of underground line.

• Journal of Electrical Engineering and Technology
• /
• v.10 no.3
• /
• pp.1293-1297
• /
• 2015

This paper introduces the insulation coordination study results for UHV AC systems which was performed by CIGRE working group. The study results will be discussed within IEC technical committee in order to amend the IEC Insulation Coordination 60071-1 Ed. 8 2010 and 60071-2 Ed. 3, 1996. This paper includes the insulation coordination of transformer, gas insulated switchgear, metal oxide arresters and clearances of transmission towers. This article also illustrates the overvoltage specific to UHV systems such as TOV(temporary overvoltage), switching overvoltage, lightning overvoltage and VFTO(very fast transient overvoltage).