基于500kV CVT内置低压电容C_3的暂态过电压在线监测

Transient Over-voltage Online Monitoring Technology Based on 500 kV Capacitive Voltage Transformer with Interior Low-voltage Capacitor C_3

为保证电网安全、稳定和可靠运行,对系统暂态过电压进行监测研究,从而采取相关措施解决其危害是具有重要意义的。文中基于500 kV电容式电压互感器(capacitor voltage transformer,CVT)对电网暂态过电压在线监测技术进行了系统研究。采取改造CVT即内置串联低压电容C3形成可靠的耦合分压装置、雷电和操作冲击试验及分析结果表明,其性能满足电网暂态监测要求。基于该分压装置研制了一套智能型暂态过电压监测系统,在实验室通过了相关性能测试,主要为开关动作的单分、单合、重合闸、分合分以及工频电压耦合操作冲击模拟试验电压波形记录。在上述基础上,结合华东电网"瓶窑500 kV变电站配串调整工程"进行了现场安装和立屏,就窑阳5438线启动调试进行了录波。最后对后期运行监测获取的电网暂态过电压典型波形进行了示例,进一步说明该在线监测技术及系统在现场长期应用的可行性和可靠性。

To ensure the secure, stable and reliable operation of a power system, it is necessary and important to research transient over-voltage monitoring technology countermeasure against the transient over-voltage. In this study, the transient over-voltage online monitoring technology based on 500 kV capacitive voltage transformer （CVT） was studied. The 500 kV CVT was modified by paralleling a low-voltage capacitor C3 to form a reliable coupled voltage divider, and lightning and switching impulse transfer tests demonstrated its effectiveness of transient over-voltage monitoring for power grid. On the basis of the voltage divider, an intelligent over-voltage monitoring system was developed, and performance tests were conducted in laboratory, including the waveforms records of simulated switching actions, such as single opening, single closing, reclosing, opening-closing-opening, and operating voltage coupled with switch impulse. Further, this transient over-voltage monitoring system was installed at the ＂string adjustment project of 500 kV Pingyao substation＂ of East China Electric Power, and was verified by start-debugging test of Yaoyang 5438 line. Some recorded typical transient over-voltage waveforms are discussed to illustrate the feasibility and reliability of the proposed online monitoring technology and system in long-term field application.