基于暂态电压监测的特高压GIL故障定位方法及工程应用

Fault Location Method and Engineering Application in UHV GIL Based on Transient Voltage Monitoring

特高压气体绝缘金属封闭输电线路(GIL)一旦发生绝缘击穿事故,精确定位击穿位置有利于事故抢修和快速恢复送电。该文提出了基于暂态电压监测的特高压GIL故障精确定位方法,并在1100kV苏通GIL综合管廊工程中实际应用,定位系统包括电压传感器、监测终端以及存储控制单元。在GIL交接试验过程中,当GIL内部发生击穿闪络时,该系统均成功触发,完整记录了绝缘击穿时所产生的暂态电压。通过波形分析发现:特高压GIL固体绝缘击穿时,暂态电压的半波陡变时间低于130 ns,并在击穿点和出线套管之间来回传播,形成典型的行波过程。通过暂态行波首次到达GIL两端测点的时间,及暂态电压的行波特征,结合行波传播速度,可计算得到故障点的准确位置,并快速解体检修。通过解体验证结果分析该系统的定位误差低于5m。由此可见,采用基于电容分压的宽频电压传感可实现特高压GIL绝缘击穿故障的快速精确定位,有助于提高特高压输电系统运行可靠性。

In case of insulation breakdown accident of ultra-high voltage(UHV) gas insulated metal-enclosed transmission line(GIL), the accurate location of breakdown position is conducive to emergency repair and rapid recovery of power transmission. This paper proposes a fault location method based on transient voltage monitoring for UHV GIL, which is actually applied in 1 100 kV Sutong GIL utility tunnel project. The system includes voltage sensor, monitoring terminal, and storage and control unit, which are successfully installed and implemented. During GIL field tests, when the GIL flashover occurs, the system successfully triggers and completely records the transient voltages generated during the breakdown. Through waveform analysis, it is found that when UHV GIL solid insulation breaks down, the half-wave steepening time of transient voltage is less than 130 ns and spreads between the breakdown point and bushing port, forming a typical traveling wave process. According to the time when the transient traveling wave first reaches the measuring points at both ends of GIL, combined with the propagation speed of traveling wave, the accurate position of the fault point is calculated and the fault point is quickly disassembled for maintenance. According to the results of disintegration verification, the positioning error of the system is less than 5 meters. It can be seen that the adoption of wide-band voltage sensing based on capacitive voltage divider can realize the rapid and accurate location of insulation breakdown faults of UHV GIL, which is conducive to improving the operation reliability of UHV transmission system.