直流系统环网接地故障检测方法

现有直流供电系统的单相接地故障检测方法,如低频信号注入法,容易受到环网的影响,导致错误的检测结果。为克服环网影响并准确检测接地故障,在传统的低频信号注入法的基础上,提出一种基于小波变换和分形理论的检测方法。小波变换用来对环流信号进行处理以划分频带,分形维数和凹凸度函数用以进行定量分析,判断是否存在环网故障。通过MATLAB程序和分形维数估算程序FD3的仿真,证明该方法可以区别正常状态与故障状态下分形维数和凹凸度值的不同。此方法克服了环网对系统的影响,适用于直流系统的接地故障检测。

Research on detection method for DC system loop net grounding fault

The prevailing method of DC system grounding fault detection,such as low frequency injection method,is prone to be impacted by the loop net in power systems,and leads to wrong detection result.In order to overcome such impact,the new detection method based on low frequency injection with wavelet transform and Fractal theory was presented.The wavelet transform is applied to deal with the signal of loop net branch current and partition different frequency.Then by utilizing fractal dimension and concavo-convex parameter,the quantitative analysis can be obtained,in order to judge whether the loop net fault occurs.The simulation results of MATLAB and PD3 show that such method can distinguish the fractal dimension and concavo-convex parameter between normal and fault conditions.This detection method can overcome the impact of loop net,and it is applicable in detecting DC system grounding fault.