A Study of Ferroresonance in the 161kV Gas Insulated Switchgear

• Main Authors: Jia-Ching Lin, 林家慶
• Other Authors: Chao-Rong Chen
• Format: Others
• Language: zh-TW
• Published: 2010
• Online Access: http://ndltd.ncl.edu.tw/handle/4dkwf7

碩士 === 國立臺北科技大學 === 電機工程系研究所 === 98 === Ferroresonance, as a non-linear resonance, is a complex electrical phenomenon caused by the saturation effect of the core components in a transformer or a voltage transformer. If not removed immediately, resonance which occurs as the nonlinear inductance changes to match the circuit capacitance will result in sustained over voltage and over current in a power system. It may further trigger a rise in the temperature and impair insulation, severely damaging equipments and endangering the safety of related personnel. The major purpose of this research is therefore to eliminate the occurrence of ferroresonance via in-depth exploration of its causes and conditions so as to reduce the risk of power system operation. A 161kV gas insulated switchgear (GIS) at a Taipower substation went through voltage transformer ferroresonance phenomenon, resulting in the voltage transformer burned and the spacer broken. Not only the equipment was damaged, the quality of power supply system was also impaired. In the thesis, the electromagnetic transients program (EMTP) is used to build an electromagnetic transients model based on the GIS-derived parameters. The same operational procedures during the accident are then adopted for simulation; the results confirm the occurrence of ferroresonance on the voltage transformer of GIS. For eliminating ferroresonance, the thesis proposes three methods, including: removing the grading capacitance of the circuit breaker, changing the GIS operational procedures, and modifying the series resistance of the damping reactor on the secondary side of the voltage transformer. Effectiveness of the proposed methods are verified by the results of separate simulations; appropriate changes do contribute to the elimination of ferroresonance and help prevent the occurenace of subsequent accidents and damages. Specific recommendations are then presented to provide reference for equipment manufacturers and operation and maintenance workers.