双回路电缆-架空线混合线路感应电压电流计算

双回路同沟电缆-同塔架空线混合线路感应电压和感应电流的计算是检修时接地刀闸选型的关键。电缆回路间感应电压电流的计算不同于架空线路。电缆金属护套对线芯具有静电屏蔽作用,根据护套接地方式不同其对线芯也具有不同的电磁屏蔽效果。文中针对220 kV双回路电缆-架空线混合线路开展运行线路对检修线路的电磁感应研究。首先根据电磁耦合推导出混合线路的感应电压、电流计算公式。其次仿真计算分析,分别研究混合线路中电缆段长度占比的变化对感应电压电流的影响;电缆护套单端接地、双端接地以及交叉互联两端接地3种接地方式对于感应电流的影响;接地刀闸等效接地电阻对于感应电流的影响。结果可为混合线路接地刀闸选型提供理论计算参考。

Calculation of induced voltage and induced current of double circuit cable-overhead hybrid line

The calculation of the induced voltage and current of the double circuit cable-overhead hybrid line is the key to the selection of the grounding switch during the maintenance. The metal sheath of the cable has the function of electrostatic shielding on the wire core, and has different electromagnetic shielding effect on the wire core according to the different grounding mode of the sheath. Therefore, the calculation of induced voltage and current between the cable circuits is different from that of overhead lines. The electromagnetic induction of the operation line to the maintenance line is studied for the typical 220 kV double circuit cable-overhead hybrid line. Firstly, according to the electromagnetic coupling, the calculation formula of the induced voltage and current of the hybrid line is derived. Secondly, the simulation model is built to analyze the influence of the length proportion of the cable section on the induced voltage and current, the influence of the three grounding modes of the cable sheath(single terminal grounding, double terminal grounding and cross interconnection terminal grounding on the induced current), and the influence of the equivalent grounding resistance of the grounding switch on the induced current. The results can provide a theoretical reference for the selection of grounding switches in hybrid line.