铁路10 kV电缆贯通线电容电流补偿度研究

对铁路沿线车站的供电，广泛采用10kV贯通线模式。贯通线是沿铁路架设、以架空线为主、小部分为电缆的辐射式输电线路。为了提高供电可靠性，近年来，贯通线中电缆比例在上升，甚至为全电缆。电缆比例的提高，显著加大了供电系统的对地电容电流，导致系统单相接地电弧不能自熄，影响中性点不接地系统瞬时故障的自动清除能力。解决贯通线的电缆电容电流带来的上述问题，通常采用在电缆部分并联星形中性点接地电抗器来补偿对地电容电流的方法。本文研究表明：现在使用的0．75补偿度方案，不能确保补偿后的单相接地电流满足电弧自熄条件。本文提出了以单相接地电弧可靠自熄为目标的补偿度选择方案，并推导出相应的补偿度选择条件。为贯通线中电缆的电容电流最优补偿，提出了计算方法。实例计算证实了所提方法的正确性。

Study on Compenstation of Capacity Currents of 10 kV Railway Continuous Power Transmission Lines

10 kV continuous power transmission lines are widely used for power supply of railway stations. The continuous power transmission lines are erected along the railway lines and mainly constructed of the overhead type. A small part of such transmission lines are cables radiating from substations. In recent years, in order to improve the reliability of power supply, the cable percentage is going up and even some continuous power trans mission lines are wholly cable lines. As a result, the ground capacitance current increases remarkably so that the ground-fault arc can not be extinguished by itself. This reduces the instant-fault self-removing ability of the neutral-ungrounded system. Wye-connected reactors with neutral-grounding are generally used to compensate the capacitance currents of the continuous power transmission lines. Our study shows that, with the 0.75 compensation ratio, the total ground-fault current in such systems may be so heavy that the ground fault arc would not be extinguished by itself. It is proposed that compensation should be aimed at self-extinction of the ground fault arc. A computational method for choosing the optimum compensation ratio to guarantee the ground-fault arc self-extinction is put forward. A case study is given to verify the proposed method.