中性点不接地电网单相接地时电压互感器损坏机理  

Mechanism of Potential Transformer Damaged in Ungrounded Neutral Power System

作　　者：林莉[1] 何月[1] 王军兵[2] 张向伍[1] 郭文宇[1] 

机构地区：[1]重庆大学输配电装备及系统安全与新技术国家重点实验室,重庆400030 [2]宿州供电公司,宿州234000

出　　处：《高电压技术》2013年第5期1114-1120,共7页High Voltage Engineering

基　　金：重庆市自然科学基金(2012jjA90006);国家重点基础研究发展计划(973计划)(2009CB724503)~~

摘　　要：中性点不接地电网中电压互感器异常损坏随电网发展呈上升趋势。为提出有效的工程防范措施以抑制该趋势,研究了这种异常损坏的机理。采用电网输电线路对地电容与电压互感器电感的并联模型替代已有的电网电容与电压互感器电感的串联模型,对电网发生间歇性单相接地时电压互感器内部的暂态过程进行了分析。由仿真计算、动模实验以及工程实验可得,在这一暂态过程中,电压互感器铁芯将进入深度饱和区,产生很大的暂态过电流。结果说明工作于中性点不接地电网中的电磁型电压互感器可能因暂态过电流导致热破坏,因此应按间歇性单相接地进行热稳定性校验。Abnormal faults of potential transformers（TVs） in ungrounded-neutral power grid show a rising tendency.In order to find effective engineering measures for suppressing this unexpected tendency,we investigated the mechanism of the abnormal faults.A model of parallel-connected TV inductor and transmission line capacitance to earth,instead of the existed models of connecting the inductor and the capacitance in series,was proposed to analyze the transient process of TV when an intermittent single-phase grounding occurred.Results of simulative calculation and experiment as well as engineering cases indicate that,during the transient process,intermittent magnetic flux drives TV core into its deep saturation zone,which will result in a large transient overcurrent.Thus,it is proposed that,in ungrounded neutral power systems,thermal stability destruction of electromagnetic TV may occur due to transient overcurrent,and the thermal stability of electromagnetic TVs should be verified under intermittent single-phase grounding situation.

关 键 词：电压互感器 中性点不接地电网 单相接地 铁磁谐振 励磁涌流 热稳定性 

分 类 号：TM451[电气工程—电器]