电力电缆极限传输长度研究

Research on the Ultimate Transmission Length of Power Cables

电力电缆不同于架空线路,其并联电容很大,导致电容充电电流大,空载运行时引起末端电压升高严重。针对该问题,基于电力电缆的正序模型,采用稳态解析分析方法研究电力电缆极限传输长度。所提出的方法适用于任何稳态运行下的有损电缆。研究发现电缆空载电压升高对200 km内电缆的限制不大。40 km以内的电缆空载末端电压升高在1%以内,与现场实测的结果相符。充电电流是限制电缆传输长度的瓶颈,然而计算结果表明,0.3补偿度两端点补偿的电缆在长度100 km时的功率因数还可以达到0.94,比目前大部分工程应用的长度60 km大很多,说明100 km的超长电缆输电线在理论上是可行的。

Different from overhead transmission lines, the power cables have large shunt capacitance, which leads to large charge capacitive current and high open end overvoltage under no-load operation condition. Based on the positive sequence model for power cables, a steady state analytical method is proposed to study the ultimate transmission length of power cables. The method proposed in this paper can calculate the ultimate length of lossy cables with different end voltages. The study shows that the open end overvohage has little limitation on the cables with a length under 200 kin. The open end overvoltage is less than 1% for the cable with a length under 40 kin, which is in good agreement with the field test. The capacitive charge current is the bottleneck for limiting the transmission length of cables. However, the calculation results show that when the compensation ratio is set at 0.3, a 100-km long cable, much longer than the 60-km long cable now in common use, can have a power factor of 0.94, indicating that the 100-km super-long cable is theoretically feasible.