高电压技术2017，Vol.43Issue(8)：2620-2629,10.DOI:10.13336/j.1003-6520.hve.20170731024
PWM整流器中性点电压偏移对小电流接地系统绝缘监测的影响
Influence of Neutral-point Voltage Deviation of PWM Rectifier on Insulation Monitoring in Small Current Neutral Grounding System
摘要
Abstract
The three-phase voltage source PWM rectifier (VSR) is key equipment in connecting the distributed generators to the small-current neutral grounding system.So,we have analyzed the frequency disturbance of the switching function as well as the change of positive-pole/negative-pole insulation for the DC side of VSR.The results demonstrate that the neutral-point voltage deviation (NPVD) of the three-phase VSR is a crucial factor which affects the response of insulation monitoring device (IMD).Thus,a pair of methods that take the mean and spectra of the neutral-point voltage as the characteristics,are proposed to detect the NPVD,one is adopted to detect the mean value of the neutral-point voltage based on DC signal injection,and the other one is adopted to determine the frequency disturbance of the neutral-point voltage based on Duffing oscillator.So,the detection result for NPVD is obtained by the variety of the characteristics mentioned above,which is induced by the deviation of the neutral-point voltage.The test results demonstrate that the neutral point deviation caused by the change of DC-side insulation balancing is the primary factor which distorts the detection of insulation resistance;the relative error of detection results obtained by IMD is less than 4％ under normal condition,and the relative error is no less than 41％ while the neutral point deviation occurs.Further,the test results certify the feasibility of the proposed method,which can be used for improving the response precision of IMD.关键词
小电流接地系统/绝缘监测/PWM整流器/中性点电压/直流注入法/混沌振子Key words
small current neutral grounding system/insulation monitoring/PWM rectifier/neutral-point voltage/DC signal injection/chaotic oscillator引用本文复制引用
严鋆,王金全,徐晔,李乾,陈凯..PWM整流器中性点电压偏移对小电流接地系统绝缘监测的影响[J].高电压技术,2017,43(8):2620-2629,10.基金项目
国家自然科学基金(51507180).Project supported by National Natural Science Foundation of China (51507180). （51507180）
