摘要
分析了低频信号注入法在直流系统环网支路接地故障检测中的局限性,提出了利用小波变换与分形理论进行环网支路接地故障检测的新方法:首先对环网支路的采样电流信号进行基于双正交b ior2.2样条小波的2次多分辨率分析,提取出环网电流信号的低频段成分特征,再计算2尺度(底层)空间概貌系数a2曲线的分形维数,以识别不同情况下的环网接地故障。该方法解决了环网中谐波电流对低频信号注入法的影响。经数值仿真分析,验证了此方法的可行性和有效性。
The paper analyzes the limitation of ＂low frequency injection＂ method for the purpose of detecting grounding fault branches in loop net in DC system, and advances a new scheme based on the wavelet transform and fractal theory. First, the scheme implements the frequency band division for current signal using multi-resolution analysis based on the bior2.2 wavelet at resolution 2 to extract the feature of low frequency band, and then calculates the fractal dimension of the scale coefficient curve a2 to judge the insulation condition of the branch, referring to change trends of fractal dimensions. This scheme overcomes the influence of harmonic current in loop net. Simulation results prove that this new method is sufficient enough for the identification of the grounding fault branches.
出处
《继电器》
CSCD
北大核心
2006年第16期17-21,共5页
Relay
基金
天津市自然科学基金资助项目(033601511)
关键词
直流系统
环网
小波
分形
盒维数
DC system
loop net
wavelet
fractal
box dimension
