Research On Fault Location Method In Non-effectively Grounded Network

The non-effectively grounded network is a popular neutral grounding mode in our country. Due to the fault signal is so weak and difficult to detect, the fault location in this system is acknowledged a difficult problem, which has not been solved successfully for many years. So the reliability and economy of distribution network are affected.After the fault characteristics of single-phase grounding in distribution system is analyzed. A fault location method for single-phase grounding using wavelet entropy is proposed. The concept of wavelet packet energy spectrum relative entropy is leaded. Then its sensibility to the frequency diversity, and its insensibility to sampling frequency and time lag are analyzed. So the wavelet entropy can be used to identify the transient current differences in the distribution automation. The process of fault location is presented, and the simulation is carried out. The results show that this method is sensitive to single-phase grounding fault of different fault conditions, it can determine single-phase ground fault location effectively.For the interphase short circuit faults, a matrix algorithm which researches the feeder section is presented. This method determines the fault location based on the network connection and overcurrent information. The algorithm is explicit,and the structure is simple.In order to determine the fault phase, a fault phase selection method based on fault current steady and transient characteristics is proposed. The theoretical analysis and simulation show that the principle is insensitive to fault time, transition resistance and fault location, the type of short circuit can be determined accurately.