Research On Single Phase-to-earth Fault Location Of Power Distribution Network With Wavelet Transform Method

With the development of society and economy, the demand for power supply and its ability has increased rapidly in recent years. Most of power distribution network system adopts the small current neutral grounding system. The research of single phase-to-earth fault location is the focus in this field nowadays.Wavelet transform is a new and promising theory in mathematics, and it has an extensive application in the power system now. It has been proved to be very efficient for transient signal analysis. According to a set of damped oscillations named "wavelets", it builds a new representation for the analyzed signal. Thought analyzing the characters of the steady signal and the transient signal after the single phase-to-earth fault occurring, we draw a conclusion that the transient signal provided with the important fault info. According to the wavelet analysis, we can find out those "hidden" info. Fault location includes two parts. One is fault line selection, the other is fault distance detection.The paper brings forward a bran-new approach for fault line selection. By transforming the zero-sequence current of fault signal, we can tell easily on which line the faults have occurred. The major point here is to compare the maximum points of the details, either their magnitudes or directions can be used to identify the fault line. Moreover, by analyzing the traveling wave after single phase-to-earth fault occurred, we put forward another approach based on current traveling wave for fault line selection. This approach is powerfully complementary for the former one, and the more important point is it achieves a theoretic identity with fault distance detection arithmetic that putting forward in the paper. The fault distance detection principle that utilizes traveling wave appears in the small-current-grounding system. Using the powerful function of wavelet in the face of singular detection, the time that the traveling wave crest arrives is detected and the fault distance detection is realized.By plenty of simulation test, the results show that the methods putting forward...