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

发布时间：2018-05-11 06:42

本文选题：小电流接地系统 + 绝缘监测　；参考：《高电压技术》2017年08期

【摘要】：三相电压型PWM整流器(voltage source PWM rectifier,VSR)是分布式电源接入小电流接地系统的关键设备。通过分析三相VSR开关函数sj的频率扰动,以及直流侧正极和负极对地绝缘状态的改变,得出了中性点电压偏移是影响系统绝缘监测装置(insulation monitoring device,IMD)响应的重要因素。据此,提出基于直流信号注入和Duffing混沌振子分析的三相VSR中性点电压偏移检测方法,该方法以中性点电压的时域平均值及频域分布状态为特征量,通过直流信号注入监测中性点电压的时域平均值,并通过Duffing混沌振子分析判别中性点电压的频域分布状态,由中性点电压偏移引起的特征量变化得出检测结果。实验分析结果表明:由三相VSR直流侧对地绝缘不平衡引起的中性点电压偏移是影响绝缘电阻检测的主要原因,当未发生中性点电压偏移时,IMD的绝缘电阻检测值最大相对误差为4%,而当发生中性点电压偏移时,IMD的绝缘电阻检测值最小相对误差为41%;采用本文提出的方法可有效检测出中性点电压偏移,为提高IMD响应精度提供依据。
[Abstract]:Three-phase voltage source PWM rectifier (VSR) is a key equipment for distributed power supply to access small current grounding system. By analyzing the frequency disturbance of the three-phase VSR switch function SJ and the change of DC side positive and negative electrode to ground insulation state, it is concluded that the neutral voltage offset is an important factor affecting the insulation monitoring de viceo IMD response of the system insulation monitoring device. Based on DC signal injection and Duffing chaotic oscillator analysis, a three-phase VSR neutral point voltage offset detection method is proposed, which is characterized by the time-domain mean voltage and the frequency domain distribution of the neutral voltage. The time-domain mean value of neutral voltage is monitored by DC signal injection, and the frequency domain distribution of neutral voltage is determined by Duffing chaotic oscillator analysis. The detection results are obtained from the variation of eigenvalue caused by neutral voltage offset. The experimental results show that the neutral voltage offset caused by the unbalanced insulation on the DC side of three-phase VSR is the main reason that affects the insulation resistance detection. The maximum relative error of the insulation resistance detection value of IMD is 4 when the neutral voltage deviation is not occurring, and the minimum relative error of the insulation resistance detection value of IMD is 41 when the neutral voltage deviation occurs. The method proposed in this paper is effective. Detected neutral voltage offset, It provides the basis for improving the precision of IMD response.
【作者单位】：解放军理工大学国防工程学院;国防科学技术大学机电工程与自动化学院;
【基金】：国家自然科学基金(51507180)~~
【分类号】：TM461;TM862

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