浅谈220 kV枢纽站变压器接地中性点选择

Discussion on the Selection of Grounding Neutral Point of Transformer in 220 kV Hub Station

中性点直接接地系统有降低过电压、提升保护灵敏性的优点,但是由于故障电流限制、保护整定等原因,变压器中性点接地的方式须调度统一管理。介绍了中性点直接接地的管理制度,分析了典型220 kV枢纽站,即双母线3台变压器并列运行的变电站,不同中性点接地方式下,电网发生故障时保护的动作情况,解释了接地中性点的优先选项。

Neutral grounded system brings lower over-voltage and high sensitivity.However,owing to its higher fault current and difficulty on relay setting,transformer neutral points grounding are limited and managed by the dispatching center.This article introduced transformer neutral grounding regulations,and illustrated a typical 220 kV load center substation,which get 3 transformer operating in parallel.By deriving relay actions when system fault occurs,and comparing the consequence of different modes of neutral grounding,it explains the prior grounded transformer neutral.