500kV断路器并联电容器的现场高电压介质损耗测量

On-site Dielectric Loss Measurements of 500 kV Circuit-breaker Capacitors Under High Voltage

断路器电容器电容及介损测量是保证断路器安全稳定运行的一项重要工作。现场测量存在感应电场严重干扰的问题,而且目前出现越来越多500kV断路器电容器按照南网预试规程在10kV测试电压下介损值超标而返厂测试又合格的情况。为解决以上问题,对改变试验电源频率来实现对现场感应电场干扰的屏蔽、电容器介损随电压的变化关系进行了理论分析,提出采用异工频试验电源和提高试验电压的方法来进行电容器电容及介损测量;基于上述测量方法,提出几种常用的现场试验方案,并分析了它们的适用范围;随后在柳东变电站对某500kV断路器电容器进行了现场电容及介损测试。试验结果表明电容器介损值随电压升高而减小,改变试验电压频率能有效屏蔽现场感应电场的干扰,采用改进的试验方法能有效解决现场断路器电容器测量中存在的上述问题。

Measurement of the capacitance and dielectric loss of the circuit-breaker capacitor is a very important task to assure safe operation of the circuit breaker. However, due to serious electric disturbance to the site measurement, more and more dielectric losses of 500 kV circuit-breaker capacitors appear over normal value under 10 kV testing voltage according to the CSG preventive trial standard. To solve problems mentioned above, we studied the shielding effect to electric disturbance when a testing power supply of different frequency from 50 Hz was used, and studied the dielectric loss variation of circuit-breaker capacitor with the applied testing voltage. By the improved testing method, we proposed two main programs for on-site dielectric loss measurement and analyzed their application situations. Moreover, we got the results of capacitance and dielectric loss measurements of circuit-breaker capacitors in Liudong transformer substation. The results showed that the improved measuring method was effective.