±800 kV特高压直流线路地线断线故障分析

Analysis of Ground Wire Disconnection Fault of±800 kV Ultra-High Voltage DC Line

提升抗冰能力对线路安全运行至关重要。对某±800 kV特高压直流线路地线断线故障现场的环境及录波进行了分析,开展了地线断口静态分析及扫描电镜试验、拉断力试验,并对导地线间距进行了仿真计算。试验和仿真计算表明:特高压直流导地线覆冰厚度差异较大,随着地线覆冰厚度的增加,导地线间间距逐渐减小,在大风作用下极易发生空气间隙不足放电。本次特高压线路故障原因为重覆冰引起导地线空气间隙距离不足,导致放电烧伤和拉断地线。微地形区线路覆冰情况可能超过设计值,应考虑现场实际覆冰厚度、导地线覆冰厚度差值、故障区段微气象和微地形等因素,确保线路设计运行有充足裕度。

To improve the anti-icing ability is vital for safe operation of the line.The paper analyzes the environment and waveform record of the ground wire disconnection fault field of±800 kV ultra-high voltage(UHV)DC line,makes static analysis of the ground wire fracture,conducts scanning electron microscope and breaking force test,and carries out the simulation calculation of guide wire spacing.According to the test and simulation calculation,there is a big difference of the ground wire icing thickness of UHV DC.When the ground wire icing thickness increases,the spacing between conductors and ground wires gradually decreases which is likely to contribute to discharge because of insufficient air gap under the strong wind.The reason for this UHV line fault is that the insufficient air gap of ground wires caused by icing contributes to discharge to burn and break ground wires.The line icing of micro-terrain region is possible to exceed the design value,so factors such as the actual on-site icing thickness,ground wire icing thickness differential value,micro-meteorology and micro-topography of fault section should be taken into consideration to ensure operation of the line.