串补隔离开关操作引起二次设备故障分析

Analysis on Common Faults of Phasor Measurement Unit Caused by Series-Compensation Isolation Switch

串补隔离开关在操作空载串补平台时,产生特快速瞬态过电压(very fast transient overvoltage,VFTO),与传统的VFTO相比,具有电弧电流大,弧隙电压大,去游离时间长等特点。由于VFTO频率与载波设备的调制频率基本一致,导致VFTO从电压互感器耦合到二次设备,引起二次设备异常甚至损坏。对串补、隔离开关、电压互感器、二次设备等建立理论分析模型,找出隔离开关操作对载波设备干扰的主要耦合路径。结合贺州串补操作导致串补采样模块、载波设备异常等现象,找出故障原因,提出应提高载波设备过压保护器MOV的容量,增大引线端子等设计建议及运维注意事项。

During the operation of series compensation isolating switches, repeated strikes of the contact gap will lead to very fast transient overvohage （VFTO） with high amplitude and steepness. The arc current and arc gap voltage by operation of isolating series compensation switches is greater respectively than those by operation of isolating no-load bus switches. The similarity between the frequency of VFTO and the coupling frequency of the carrier equipment leads to the abnormity and even damage of the carrier equipment by the VFTO coupling from the capacitor voltage transformer, A theoretical analysis model is established for series compensation switches, capacitor voltage transformer and carrier equipment to find out both the coupling path of the VFI＇O and the cause of the carrier equipment problems. Suggestions are proposed to improve the capacity of MOV for the overvoltage protection and to increase the lead terminals for design, operation and maintenance.