基于等效半波注入法的小电流接地故障选线

Small current grounding fault line selection based on equivalent half wave injection method

我国中压配电网多数采用小电流接地运行方式,由于小电流接地系统单相接地故障电流很小并且容易受到外界条件的干扰等原因,故障选线难题多年未得到有效解决。通过对目前已有的故障选线方法进行分析,在原有的直流注入原理的基础上形成了等效半波注入法,通过比较各条线路的零序电流来选线。对等效半波注入法的选线定位理论进行了分析,主要包括确定了注入的半波直流信号的流通路径、形成了该方法的等值电路,并组建了对应的数学模型,在原理上验证了该理论的正确性。最后通过Matlab搭建模型验证该方法能够准确地实现故障选线。

Most of the medium voltage distribution networks in China adopt the small current grounding mode.Because the single-phase grounding fault current of small current grounding system is very small and easily disturbed by external conditions,the problem of fault line selection has not been effectively solved for many years.Based on the analysis of the existing fault line selection methods,the equivalent half-wave injection method was formed on the basis of the original DC injection principle,and it selected the line by comparing the zero sequence current of each line.The theory of line selection and location based on equivalent half-wave injection method was analyzed,which mainly included determining the flow path of injected half-wave DC signal,and the equivalent circuit of the method was formed.After that,a corresponding mathematical model was established.Finally,the correctness of the theory was verified in principle.Finally,a model is built by MATLAB to verify that the method can accurately and reliably achieve fault line selection.