直流微电网系统电弧故障特征及检测方法

Arc Fault Characteristics and Detection Method of DC Microgrid System

直流微电网电弧故障发生位置分散,易被变换器高频噪声淹没,难以进行检测。针对现有直流电弧故障保护方法在直流微电网中应用时存在误动作和拒动作的问题,搭建直流微电网故障电弧实验平台,开展了不同位置串并联故障电弧实验,从时频域角度对直流微电网故障电弧信号特性进行研究,采用快速傅里叶变换(fast Fourier transform,FFT)分析微电网直流母线电流信号,将得到的频谱进行分段积分,将电弧信号10 Hz~10 kHz、20~30 kHz、40~50 kHz这3个特征频段积分值作为第一特征,采用互补集合经验模态分解(complementary ensemble empirical mode decomposition,CEEMD)算法进行时频分析,将母线电流信号分解成若干各本征模态分量(intrinsic mode function,IMF),计算各分量能量值,比较分析选取局部分量IMF7和IMF8的能量作为第二特征。在此基础上,提出基于阈值比较的故障电弧检测方法。研究结果表明:所提方法能够准确实现不同位置的串并联故障电弧检测,且在负载投切和变换器动态调整时未发生误判,为开发可靠的电弧故障检测与灭弧装置提供参考.

DC microgrid arc faults occur in scattered locations and are easily submerged by high-frequency noise of the converter,making it difficult to detect.In view of the problems of misoperation and rejection in the application of existing DC arc fault protection methods in DC microgrid,we built a DC microgrid fault arc experimental platform,carried out series and parallel fault arc experiments at different positions,and studied the DC microgrid fault arc signal characteristics from the perspective of time and frequency domain.Furthermore,the fast Fourier transform(FFT)was used to analyze DC bus current signals of microgrid,and the obtained spectrum was segmentally integrated.Complementary EEMD(CEEMD)algorithm was used for time-frequency analysis by using integral values of the three characteristic frequency bands of the arc signal 10 Hz~10 kHz,20~30 kHz,and 40~50 kHz as the first characteristic.The intrinsic mode function(IMF)was used to calculate the energy of each component,and the energy of local components IMF7 and IMF8 was compared and analyzed as the second characteristic.On this basis,a fault arc detection method based on threshold comparison was proposed.The results show that the proposed method can be adopted to accurately detect arc faults at different positions and in series and parallel,and no misjudgments occur during load switching and dynamic adjustment of the converter,which provides a reference for the development of reliable arc fault detection and arc extinguishing devices.