500 KV GIL Fault Location Based on Single Terminal Transient Monitoring in Field Takeover Test

In this study, the fault location method in 500 kV gas insulated transmission line (GIL) based on single terminal transient voltage and current monitoring was proposed. The measurement bandwidth of the transient voltage and current sensing system is 2.1 Hz ~ 230 MHz and 100 MHz ~ 500 MHz respectively. The time and frequency domain feature of transient voltage and current generated by GIL breakdown is analyzed. It is found that when insulation breakdown occurs in the 500 kV GIL, the first change steepness of the transient voltage is less than 60 ns. A typical traveling wave process is formed when the transient voltage spreads between the break point and bushing. The accurate position of the fault point can be calculated based on the time when the transient traveling wave reached the measuring points and the propagation speed of traveling wave. According to the results of disintegration verification, the fault position is determined. The results show that the positioning error based on transient voltage is less than 2 m, the error based on transient current is approximately 5 m.