【摘要】 分析了低频信号注入法,并且针对其缺陷提出了基于小波变换的检测方案。即当接地故障发生后,向直流系统正负母线注入低频正弦电压信号,利用套在各支路的电流互感器检测出支路中的低频电流信号,通过小波变换算法从中提取出与注入信号同频的正弦电流信号。计算出该电流信号中的阻性分量即可求得该支路的接地电阻值,从而可以判断出故障支路。该文讲述了将小波分析应用于直流系统接地故障检测的基本过程和主要结果,并通过大量的数值仿真和实际的实验研究验证了基于小波变换的直流系统接地检测方法的可行性。更多还原

【Abstract】 The paper analyzes the method of low frequency signal injection, which is usually used to detect DC system grounding fault, and advances the method based on wavelet transforms. That is when the grounding fault occurs, the sine voltage signal with low frequency is injected into the positive bus and the negative bus, the current signal existed in each branch is detected by the current transformer that is installed on the top of the branch, and the complex wavelet transform algorithm extracts the sine current signal that has the same frequency with the injected signal from each branch current. After the value of the resistance current that is included in the extracted current can be calculated to get the value of each branch’s insulating resistance, the faulted branch will be found out . The paper depicts the whole thought of the detection process and the main result. Simulations by Matlab verify that it can get the phasor characteristics of the low frequency current exactly in the case of high direct earth capacitance and the faulted branch will be found out accurately.更多还原