GIS现场验收及运行中若干问题的研究

Some Problems Research of GIS On-site Acceptance and in Operation

由于GIS的一系列优点,使其在各个电压等级中得到了广泛的应用。文中首先针对超高压GIS站现场冲击绝缘试验中的试验波形进行了模拟计算、图解分析,说明了现场冲击试验的波形与GIS的管母线长度密切相关,冲击试验前应对试验区域进行模拟计算、同时根据模拟计算结果选择合适的冲击试验波类型;其次,对现场充电试验中出现的电磁式电压互感器(PT)的铁磁谐振现象进行了分析,认为断路器断口间加装的均压电容、PT所连母线过短以及断路器切断PT所连母线时的相位角是引起PT铁心磁饱和、致使PT铁磁谐振的主要原因;再次,对GIS运行中相同位置三相避雷器(LA)的动作次数不同进行了分析,认为主要是由于系统中A、B、C三相电源相位角相差120°,从而使断路器动作瞬间在三相上所产生的操作过电压幅值不同、由此流过各相LA的冲击电流值不同所致;最后,对绝缘子沿面小溪状的爬电痕迹进行了解读,认为起因于断路器断口间加装的并联电容或/和邻近送电线路对空载线路的感应,使受电弧分解物侵蚀的绝缘子表面持续流过数值不高、但时间较长的感应电流所致。通过对GIS现场验收及运行中这些问题的研究,为GIS的安全运行提供了具有参考价值的理论基础及实践依据。

Due to a series of advantages of GIS, it is widely used in various voltage levels. In this paper, the simulative calculation and graphic analysis of the test waveforms obtained from the GIS field impulse insulation test is conducted firstly, which illustrates that the impulse test waveform is closely related to the GIS pipe-bus bar length. The test area should be simulated before field impulse test and the appropriate impulse test wave type is selected according to the results of simulation calculation. Secondly, the ferromagnetic resonance phenomena of electro- magnetic voltage transformer（PT）are analyzed in site charging test. It is considered that the breaker＇s inter electrode capacitance, too short bus connection to PT and the phase angle when the circuit breaker cutting off the PT are the main reason that cause PT core magnetic saturation and result in PT ferro-resonance. Thirdly, the different action times of the three-phase lightning arrester（LA）at the same position in GIS operation are analyzed. It is con- sidered that the main reason is due to the phase angle difference 120~ in three phase power system, which results in that the three phase switching overvohage peaks are different at the breaker switching instant. And the impulse currents of three phase LAs installed in the same place are different. Finally, the stream shape creepage trace oc- curred on the insulator surface are explained. It is considered that arises from the breaker＇s inter electrode capaci- tance and/or induction of adjacent transmission lines to no-load lines and results in the induced current flowing continuously on the insulator surface corroded by the arc decomposition, such current value is not high but the duration is longer. Through these problems research in GIS site acceptance and operation, it may provide theoretical basis with reference value and practical evidence for the safe operation of GIS.