特高压直流输电系统接地极线路保护配置方案优化建议

Optimization Suggestions for Line Protection Strategy Configuration of Grounding Electrode in UHVDC Transmission System

接地极是特高压直流输电系统中重要的组成部分,结合宾金直流接地极调试及投运以来发生的两起接地极引线断线事件,尤其是2015年7月13日接地极引线1断线接地事件,利用单位电流法计算故障支路的电流分布系数,理论分析接地极线路接地和断线故障时电流变化特征,深入分析目前宾金直流接地极保护策略配置存在的缺陷,将纵联差动保护与不平衡保护相结合,形成一种能准确判断故障类型的新型保护配置方法,优化目前的保护动作策略,能有效提高接地极系统运行的稳定性。

Grounding electrode is the most important part of UHVDC transmission system. The comprehensive analysis for two broken faults in grounding electrode wire of Bin - Jin transmission system is given which ocurred in commissioning period and operation period, especially broken fault ocurred in line - 1 on July 13, 2015. The change characteristics of current with ground fault and broken fault in grounding line are analyzed by using unit current method to calculate the current distribution factor of fault branch. Based on deeply analysing the defects of current protection configuration and action strategy, a new pro- tection configuration is proposed combing with longitudinal differential protection and unbalance protection. The method can judge the fault type accurately. And also the optimized action strategies is given which will effectively improve the stability of the grounding electrode system.