特高压交流单相接地故障过电压计算及限制方法

Calculation and suppression of single-phase grounding overvoltage in UHVAC system

基于系统电源阻抗特性对单相接地故障过电压的影响规律,提出了综合考虑该过电压的各影响因素后求取单相接地故障过电压最大值的方法,利用该方法可以在较少的仿真计算量下准确地求出单相接地故障过电压最大值。对不同长度线路的单相接地故障过电压的限制问题进行了探讨,并从综合考虑工频过电压和操作过电压的角度提出了沿线高抗补偿容量的最优分配方案,最后对单回线路与双回线路的单相接地故障过电压进行了比较,提出了相应的过电压限制措施。结果表明线路长度小于500 km时,采用线路两端设置高抗和金属氧化物避雷器(MOA)的措施,即可有效限制该过电压;当长度超过600 km时,需在长线路中间进行分段落点,设置MOA及合适的高抗补偿容量来限制该过电压,分段距离宜控制在400 km左右;相同长度下,单回线路的单相接地故障过电压较双回线路严重。

Based on the effect of power source impedance on single-phase grounding overvohage,a method to accurately calculate the maximum single-phase grounding overvoltage with less simulative computation is proposed,which considers various influencing factors synthetically. The suppression of single-phase grounding overvoltage is studied for different line lengths and the optimal allocation of HV（High Voltage） shunt reactor compensation capacity along line is proposed from the aspect of both frequency overvoltage and switching overvoltage. The single-phase grounding overvoltage is compared between single-loop and dual-loop lines, which shows that of former is serious than that of latter,and the corresponding countermeasures are given： MOA（Metal Oxide Arrester） and HV shunt reactor should be installed at both ends for line with length less than 500 km;distributed MOA and HV shunt reactor installed for each segment of line with length greater than 600 km,the length of line segment should be about 400 km.