高压直流输电系统双极中性母线差动保护改进方案研究

为提高直流输电系统双极中性母线差动保护运行可靠性,针对双极中性母线差动保护性能存在缺陷,提出保护的改进方案。由于双极中性母线差动保护存在缺陷,曾导致多起单一元件故障引发高压直流输电系统单、双极强迫停运事件。结合具体停运事件,对双极中性母线差动保护性能进行分析,包括:1)保护引入非电量信号的必要性及方式;2)双极运行工况下,保护经控制极判据开放的逻辑以及闭合双极中性母线接地开关的动作策略。根据分析结果,提出保护的改进方案,保护改进方案在提高保护运行可靠性的同时,兼顾了改善直流输电系统运行维护工作的效率。目前,改进方案已在多个高压直流输电系统中实施,采用该方案后,双极中性母线差动保护运行情况良好。

Research on bipolar neutral bus differential protection improvement scheme in HVDC transmission system

In order to improve the bipolar neutral bus differential protection reliability, the improvement measure of protection is proposed according to the existed deficiency. The bipolar neutral bus differential protection performance exists deficiency, which has led to monopole or bipolar forced outage event by one component fault. The performance of bipolar neutral bus differential protection is analyzed combining with actual forced outage events, which includes: 1) the necessity and way of non-electricity signals adopted by protection; 2) the protection logic of blocking by control pole criterion and operating strategy of closing NBGS in the case of bipolar operation. According to the analysis results, the improvement measure of protection is proposed. The measure can be not only improve protection reliability, but also increase the efficiency of HVDC maintenance work. At present, the measure is implemented in multiple HVDC system, and then the bipolar neutral bus differential protection of these HVDC system operates well after adopting the measure.