变压器中性点过电压分析与绝缘配合  

Overvoltage analysis and insulation coordination of transformer neutral point

作　　者：杨智 詹江杨 徐星 玉林威 邹国平[2] 陈向荣 Yang Zhi;Zhan Jiangyang;Xu Xing;Yu Linwei;Zou Guoping;Chen Xiangrong(State Grid Zhejiang Electric Power Research Institute,Hangzhou 310014,China;Zhejiang Provincial Key Laboratory of Electrical Machine Systems,School of Electrical Engineering,Zhejiang University,Hangzhou 310027,China)

机构地区：[1]国网浙江省电力有限公司电力科学研究院,杭州310014 [2]浙江大学电气工程学院浙江省电机系统智能控制与变流技术重点实验室,杭州310027

出　　处：《电测与仪表》2023年第10期30-35,共6页Electrical Measurement & Instrumentation

基　　金：国网浙江省电力有限公司科技项目(5211DS180039)。

摘　　要：电力系统发生不对称短路、非全相运行和雷击等故障时,变电站变压器中性点会出现较高的过电压,严重影响中性点绝缘的可靠性,因此需要对变压器中性点过电压和绝缘配合开展研究。文章在PSCAD/EMTDC中搭建110 kV输电系统仿真模型,计算分析线路发生各种故障时的中性点过电压,依据仿真所得过电压值,确定放电间隙距离以实现更加优化的绝缘配合。结果表明,线路发生单相接地故障时中性点最高过电压为117.73 kV;发生单相断线时中性点最高过电压为52 kV;发生雷击时中性点最高过电压为118 kV;采用放电间隙并联避雷器的中性点保护方式时,选取放电间隙距离为13 mm~14 mm时能达到最优的绝缘配合效果。该研究结果可以为110 kV变压器中性点的绝缘配合优化提供重要的理论和实验参考依据。When the 110 kV power system suffers from asymmetrical short circuit,non-full-phase operation,and lightning strikes,a large overvoltage will appear at the neutral point of the transformer in the substation and endanger the neutral point insulation.Therefore,it is necessary to study the over-voltage and insulation coordination of transformer neutral points.This paper builds a simulation model of 110 kV power transmission system in PSCAD/EMTDC,calculates and analyzes the neutral point overvoltage when various faults occur on the line,and determines the discharge gap distance based on the obtained overvoltage value to achieve good insulation coordination.The calculation results show that the maximum overvoltage at the neutral point reaches 117.73 kV when a single-phase ground fault occurs on the line;the maximum overvoltage at the neutral point reaches 52 kV when a single-phase disconnection occurs;the maximum overvoltage at the neutral point reaches 118 kV when a lightning strike occurs;a better insulation coordination effect can be achieved when the discharge gap distance is 13 mm~14 mm with the parallel arrester.The research results can provide important theoretical and experimental reference basis for insulation coordination of 110 kV transformer neutral point.

关 键 词：110 kV输电系统 变压器中性点 过电压 放电间隙 绝缘配合 

分 类 号：TM922[电气工程—电力电子与电力传动]