A Fast Faulty Phase Selection Method Considering Fault Tolerance for Single Phase to Ground Fault in Distribution Networks

Faulty phase selection (FPS) methods are used to solve the problem of single phase to ground fault (SPGF) in the distribution network. When a false FPS (FFPS) issue occurs, the short-circuit current in the faulty line suddenly increases. It is crucial to diminish damages caused by the FFPS issue and rapidly reselect the faulty phase. Therefore, this article proposes a fault-tolerant method based on an active-intervention-type arc suppression device with a soft switch mode (AASD-SSM) and a fast FPS method based on wavelet packet transform (WPT). To strengthen the fault-tolerant performance of FPS, the AASD-SSM is first developed with an intermediate resistance and a soft switch. Then, the value of intermediate resistance is determined by the short-circuit current in AASD-SSM. To realize the accuracy and rapidity of FPS, a modified WPT (MWPT) method based on frequency band energy is presented. In different fault scenarios, the number of wavelet decomposition layer is updated by MWPT, and the SPGF issues in the faulty lines can be monitored in real time. Simulation results demonstrate that the AASD-SSM improves the fault-tolerant performance of FPS. The phase selection accuracy of MWPT is better than that of WPT in all fault scenarios, and the computational complexity of MWPT is reduced for more than 10%.