高压单芯电缆单相接地故障护套过电压特性仿真分析

Simulation analysis of sheath overvoltage characteristic for single-phase ground fault in high voltage single-core cable

高压单芯电力电缆在敷设过程中,为了限制感应电压、增加单段电缆长度、减少中间接头数量,金属护套层往往采用交叉互联接地。若电力电缆发生单相接地故障,在交叉互联点会感应出较高的过电压,影响电缆使用寿命。对此利用电磁暂态软件EMTP,研究了在单相接地故障情况下高压单芯电缆金属护套过电压特性,分析了电缆整体排列方式、接地电阻、负荷性质、交叉互联各小段电缆长度以及混合排列方式对金属护套过电压的影响程度。研究结果表明:电缆整体排列方式、交叉互联各小段电缆长度和混合排列方式对金属护套过电压的影响较大;接地电阻和负荷性质对感应过电压的影响较小。

When the high-voltage power cable is in the laying process,in order to limit the induced voltage,increase the length of a single cable and reduce the intermediate connector,the metal sheath is usually grounded at two terminals with cross-bonding. If the power cable occurs single-phase ground fault,the high over-voltage is induced at the cross-bonding point,and it is harmful to insulation performance. This paper analyzes metal sheath overvoltage characteristics of the high-voltage single-core cables when there is a single-phase ground fault by electromagnetic transient calculation program EMTP. The effects of cable arrangement,grounding resistance,character of cable load,crossbonding cable length and mixed arrangement on the overvoltage of metal sheath are also studied. The research result indicates that the cable arrangement,cross-bonding cable length and mixed arrangement have greater impact on the metal sheath over-voltage,and the grounding resistance and characteristic of cable load have little effect on the metal sheath induced overvoltage.