500kV主变压器中性点经小电抗接地限制单相短路电流效果分析

Analysis on Limiting Effect of Neutral Grounding via Small Reactance for 500 k V Main Transformer on Single-phase Short-circuit Current

针对成都电网500 k V变电站200 k V母线单相短路电流超过三相短路电流、甚至超过开关遮断水平的问题,分析其产生的原因,提出了主变压器中性点经小电抗接地抑制单相短路电流的措施。根据四川规划电网数据,运用电力系统分析综合程序软件(PSASP),分析了500 k V自耦变压器中性点经小电抗接地方式对220 k V侧单相短路电流的限制效果,以及中性点经小电抗接地对中性点绝缘水平的影响,并对小电抗选取值提出指导意见。

Aiming at the issue that single- phase short- circuit current at the 220 k V bus of Chengdu 500 k V substation exceeds the three- phase short- circuit current or even exceeds the breaking capacity of breaker,the reasons are analyzed and the measures of neutral grounding via small reactance for main transformer is put forward to reduce the single- phase short-circuit current. According to the planning data of Sichuan power grid,the limiting effects of neutral grounding via small reactance for 500 k V autotransformer on 220 k V single- phase short- circuit current are analyzed using the power system analysis software package（ PSASP）. The influence of neutral grounding via small reactance on insulation level of neutral point is also analyzed,and a directive idea about value selection of small reactor is propoased.