Mesh fractal dimension detection on single-phrase-to-earth fault in the non-solidly earthed network

The most frequent fault type is single-phrase-to-earth fault in the non-solidly earthed network. After analyzing the characteristics of the existing methods about identifying the faulted line in the non-solidly earthed network, the characteristics of the fault-current waveforms are analyzed deeply and a new method using mesh fractal dimension is presented. The mesh fractal dimension of zero-order currents of faulty line and normal line are calculated and compared, the faulted line can be determined correctly. The selecting result on fault feeder is out of all relation to the CT´s polarity. The new method is right to be applied to neutral point unearthed system and neutral point ineffective earthed system. The fault line can be confirmed even when intermittent arc earth faults occur. Simulations of various earth faults under different conditions are performed using MATLAB. The results show the method is feasible and effective.