基于DOST能量相对熵的配网单相接地故障选线方法

针对小电流接地故障中,不同类型配电线路故障特征频带能量分布不一致的情况,提出一种基于离散正交S变换与能量相对熵的故障选线方法。首先提取各线路故障后首半个工频周波的暂态零序电流,利用离散正交S变换计算暂态零序电流各频带的变换系数及各频带暂态能量,结合能量相对熵对两个波形细微区别的识别能力,分别获取各线路在不同频带的能量相对熵,并综合得到每条线路的综合能量相对熵,据此熵值大小进行故障选线。Matlab仿真表明该方法不受接地电阻、故障初始角、故障距离等条件的影响,在间歇性电弧故障时仍然可准确实现线-缆混合线路单相接地故障选线。

Method of Distribution Network Single-Phase Ground Fault Line Selection Based on Discrete Orthogonal S-Transform and Relative Entropy of Energy

The frequency band energy of different lines shows inconsistent distribution when single-phase earth fault occurs. To solve this problem this paper proposes a fault line selection method which combines discrete orthogonal S-transform with the relative entropy of frequency band energy. Firstly,based on half cycle of the zero-sequence current of every line after single-phase earth fault occurs, the method calculates the transform coefficients of each frequency band with the method of discrete orthogonal S-transform and then calculates the value of transient energy accordingly. Secondly, combine with the great signal recognition ability of relative entropy, the relative entropy of energy in different frequency bands of every line are respectively calculated which compose the relative entropy of integrated energy for each line, then the fault line chosen based on the integrated values. Matlab simulation shows that this method is free from the influence of ground resistance, fault time and fault distance, it can realize the accurate selection of fault line for single-phase earth fault in wire-cable mixed lines even when intermittent arc fault occurs.