特高压空载变压器谐振过电压和励磁涌流分析及抑制方法

为研究从1 000kV侧合闸空载特高压(UHV)变压器的暂态特性,并确定其过电压和励磁涌流的幅值,从而为以后运行中合闸空载变压器的操作方式提供技术依据,首先将特高压交流试验示范工程系统调试时合空变过电压和励磁涌流的实测结果与模拟计算结果进行了对比,并找出了合理的的变压器励磁曲线和剩磁取值以提高仿真模型的准确性,在此基础上进行了合闸空载变压器的模拟计算。结果表明,变压器励磁曲线的电压不宜取得过低,变压器剩磁宜取40%～50%。将所选取的变压器励磁曲线和剩磁运用到特高压交流试验示范工程扩建工程的合空变研究中,并计算了从1 000kV侧合闸特高压空载变压器的过电压和励磁涌流。研究结果表明,合闸特高压空载变压器产生谐振过电压的可能性比合闸500kV变压器大,长治站和荆门站特高压空载变压器合闸均没有出现谐振过电压,而南阳站合闸第2台特高压变压器时产生了标幺值>1.3(基准值为(槡2×1 100/槡3)kV)的谐振过电压,并且基本上不衰减;合闸电阻可有效地抑制该谐振过电压;合闸时产生的励磁涌流均不大。

Analysis and Suppression Method of No-load Ultra High Voltage Transformer Resonance Overvoltage and Inrush Current

In order to study transient characteristics of closing no-load ultra high voltage(UHV) transformer on the 1 000 kV side and to get the magnitude of overvoltage and inrush current,so as to provide technical basis for operation of closing no-load transformer,we compared actual measurement results with calculated results of UHV AC pilot project,and obtained reasonable transformer excitation curve and remnant magnetism value,which could improve accuracy of simulation model.Moreover,we simulated and computed the closing no-load transformer.Results indicated that voltage of excitation curve should not be low,and the remnant magnetism value should be chosen between 40%~50%.The chosen transformer excitation curve and remnant magnetism value were applied to the extension project of UHV AC pilot project,and the overvoltage and inrush current while closing no-load UHV transformer on the 1 000 kV side were calculated.Results showed that the probability of resonance overvoltage of closing UHV transformer was higher than that of 500 kV transformer,and there was no resonance overvoltage while closing UHV transformer in Changzhi or Jingmen Substation,however,the resonance overvoltage of per unit value was higher than 1.3(reference value(2×1 100/3) kV) while closing the second transformer at Nanyang substation.In addition,the closing resistor could effectively restrain resonance overvoltage,and the inrush current was small.