高速铁路全电缆电力贯通线的电容电流及其容性无功补偿分析

Analysis of Capacitive Current and Capacitive Reactive Compensation in the Medium- voltage of All-cable Through Line on High- speed Railway

在高速铁路电力供配电系统中,采用全电缆贯通线方案供电系统可靠性得以大幅提高的同时,电容电流过大会带来末端电压超标、容性无功增加、系统效率降低、操作过电压、单相接地故障下的电弧过电压等一系列问题。文章针对高速铁路电力贯通线的常见配置,在正常运行和单项接地故障情况下,对电缆线路电容电流分布及其参数水平予以分析。并通过对单芯电缆和三芯电缆方案的电容电流水平差异进行理论分析和比较,得出全线路单芯电缆敷设方案在可靠性上具备明显优势的结论。并提出了在工程设计中的电抗器补偿容量计算、补偿后电容电流的校验以及供配电系统中性点接地方式选择的建议。

Though the reliability of power supply system with all-cable through line is improved greatly, a series of prob-lems occur, such as terminal overvoltage, increasing of capacitive reactive power, lower system efficiency, switching ov-ervoltage and arc overvoltage under single-phase grounding fault due to excessive capacitive current in the power supply system of high-speed railway. According to common configuration of power through line on high-speed railway, an analy-sis is made on distribution and parameter level of capacitive current of cable line under normal working conditions and single-phase grounding fault. The theoretical analysis and comparison are made on horizontal difference of capacitive cur-rent between single-core cable and three-core cable, through analysis and comparison, it is concluded that single-core cable is more reliable than three-core cable. Suggestions are given for calculation of reactor compensating capacity, veri-fication of compensated capacitive current and selection of neutral point grounding mode in the engineering design.