暂态电压监测

水电站出线遭受雷击时将产生严重的雷击侵入过电压，站内GIS（气体绝缘组合电器）隔离开关和断路器操作也将激发VFTO（特快速暂态过电压），严重威胁GIS及变压器设备的绝缘安全。为此，在水电站主变压器高压侧的GIS设备上增设超宽频暂态电压传感器，构建水电站暂态电压在线监测系统，完整记录水电站出线遭受雷击时的站内暂态响应过程。通过对暂态电压时域和频域特征分析发现：水电站出线遭受雷击接地故障时，断路器可能出现断口重燃；基于侵入水电站的雷击暂态电压波形可实现准确的故障单端定位，当线路雷击距离水电站10 km以内时，侵入水电站内部的暂态电压将威胁变压器绝缘。利用超宽频暂态电压监测系统可准确记录水电站内异常暂态事件，通过各测点暂态波形的时域和频域特征对比分析，可定位暂态激励源位置，有助于发现设备异常并及时预警，保障设备运行可靠性和水电稳定外送。 When lightning strikes the outgoing lines of a hydropower station, it induces severe overvoltages. Then, the operation of gas-insulated switchgear(GIS) and circuit breakers within the station also triggers very fast transient overvoltages(VFTO), posing a significant threat to the insulation safety of GIS and transformer equipment. To address this, an ultra-wideband transient voltage sensor is installed on the high-voltage side of the GIS equipment at the main transformer of the hydropower station. This establishes an online monitoring system for transient voltages, capturing the transient response process in the hydropower station during lightning strikes on its outgoing lines.Through the analysis of time domain and frequency domain characteristics of transient voltage, it is observed that when the outgoing lines of the hydropower station experience a lightning-induced ground fault, fracture reignition may occur in the circuit breaker. Based on the waveform of the lightning transient voltage infiltrating the hydropower station, accurate single-end fault location can be achieved. When the lightning strike on line

为研究特高压气体绝缘金属封闭输电线路在交接耐压试验和运行时绝缘击穿激发的暂态电压特征,利用在1100kV苏通GIL综合管廊工程安装的超宽频暂态电压监测系统,准确测量了GIL在耐压试验和运行时绝缘击穿所产生的暂态电压。分析了GIL在不同工况下典型绝缘击穿所产生暂态电压时域波形的持续时间、变化陡度以及幅值衰减特征。通过傅里叶变化分析了暂态波形的频域特征,发现特征频率与故障位置紧密相关。最后通过连续小波变换分析了暂态电压的时频特征,发现陡变电压的瞬时频率均超过了3MHz,可通过暂态电压的时频分布图准确判断GIL是否发生次生放电。通过对暂态电压时域和频域特征分析,有助于弄清GIL绝缘故障时暂态电压行波激发及传播特征,准确评估暂态电压对GIL的绝缘危害,提高特高压GIL运行的可靠性。