一起电容式电压互感器绝缘在线监测案例分析

Analysis of an On-line Monitoring Insulation Case of Capacitor Voltage Transformer

电容式电压互感器(CVT)是变电站的重要设备,测量其介质损耗因素和电容量可以及时发现设备的绝缘缺陷。但是由于其特殊的绝缘结构,使得诊断变得更加复杂。针对这个问题,笔者通过一起CVT的案例,基于测量的原理和基本结构,分析了电容单元在出现故障时,介质损耗因素和电容量的在线监测数据明显变化,而离线测量介质损耗因素的数据基本不变。对电容量明显变化的原因,提出了相应的预防事故措施。同时,验证了在线监测CVT数据的可靠性和有效性。

Capacitor vohage transformer is major substation equipment. Measuring their dielectric loss angle and capacitance can help one timely detect insulation defects in the equipment. However, its special insulation structure makes the diagnosis more complicated. In this paper, a fault case of capacitor voltage transformer is analyzed based on the principle of measurement and the structure of measuring device, and the result indicates that the on-line monitoring data of dielectric loss factor and capacitance change obviously when a fault happens in capacitor, while the off-line detecting data of dielectric loss factor keeps stable but capacitance changes clearly. The reliability and effectiveness of the on-line monitoring method for capacitor voltage transformer is verified. Some countermeasures against the cause corresponding to the clear variation of capacitance are suggested.