Fault Accurate Location Method in UHV GIL Based on Transient Voltage Travelling Wave

Abstract

In case of insulation breakdown accident of ultra-high voltage (UHV) gas insulated metal-enclosed transmission line (GIL), accurate location of breakdown position is conducive to emergency repair and rapid recovery of power transmission. This paper proposed the fault location method based on transient voltage travelling wave, which is actual applied in 1100kV Sutong GIL utility tunnel project. During the operation, when the GIL flashover occurred, the transient voltage generated during the breakdown was completely recorded. Through waveform analysis, it is found that when UHV GIL insulation breaks down, the first change steepness of transient voltage is less than 700ns, and spreads between the break point and bushing, form a typical traveling wave process. Through the time when the transient traveling wave first reached the measuring points at both ends of and combined with the propagation speed of traveling 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 transient voltage sensing can realize the rapid and accurate location of insulation breakdown fault of UHV GIL, which is conducive to improving the operation reliability of UHV transmission system.