故障后中性点不接地变压器快速送电的过电压分析

变电站现场运行规程明确规定在进行变压器恢复供电操作时,中性点不接地的变压器需要专人到现场合中性点开关,耗时较长。为研究缩短变压器恢复供电操作时间的可行性,通过PSCAD电力系统仿真软件建立了110 kV变电站的仿真计算模型,在此基础上开展主进线路故障后变压器恢复供电操作时中性点过电压的仿真计算,分别考虑了三相非同期合闸和负荷率对中性点电压的影响,计算结果与规定的绝缘水平进行对比后,认为当外部故障导致主变压器失电时,自动装置未动作或失败的情况下,排除线路故障后可以采用直接合闸送电的方式,快速恢复变电站供电。

Overvoltage Analysis on Neutral Point Ungrounded Transformer Fast Recovery Power Transmission After Fault

The on-site operation procedures of substation clearly stipulate that when the transformer recovers its power supply,the transformer with ungrounded neutral point needs special personnel to close the neutral point breaker on the site,which takes a long time.In order to study the feasibility of shortening the operation time of the transformer to restore power supply,this paper firstly establishes the simulation calculation model of 110 kV substation by PSCAD,and then carries out the simulation calculation of the overvoltage of the neutral point when the transformer restores power supply after the main incoming line fault,taking into account the influence of three-phase asynchronous closing and load rate on the neutral point voltage respectively.After comparing the calculation results with the specified insulation level,it is concluded that when the main transformer loses power due to external fault,under the condition that the automatic device does not act or fails,after eliminating the line fault,the way of direct closing and sending can be adopted to quickly restore the power supply of the substation.