Research On Single-phase To Ground Fault Line Selection And Location In Distribution Networks

Power users connect to transmission system by power distribution network.So it is significant for national economy and human life to keep the distribution network operating safely and reliably.The non-effectively grounded power system is widely used in the distribution network in China due to its high reliability.For 80% of the faults in power distribution network are single phase earth faults,problem such as fault line selection and fault location shows great importance.This paper analyzes the zero sequence current distribution of the non-effectively grounded power systems when single-phase earth fault occurs.In addition,the concept of line equivalent length is also introduced.The line equivalent length,which is taken as state quantity of strong tracking filter,is estimated by strong tracking filter for its excellent performance.Then the fault line selection is realized by judging the equivalent length of each line.After the fault line selection,the line equivalent lengths of all measuring points on the fault line are estimated by strong tracking filter to achieve fault section location.Support vector regression algorithm is applied to achieve the fault location for the single phase earth fault of the distribution network.The fault line's head-end zero-sequence current is decomposed by wavelet packet to obtain the four levels' energy of wavelet packet.Then the input and output of the support vector regression algorithm is reasonably selected by analyzing the relationship between the energy of each frequency band and the fault distance,the fault resistance and the fault time.Based on setting the training samples of different fault conditions,a fault location model by support vector regression algorithm is established.To verify the accuracy of the above algorithms,a distribution network model is established and different fault conditions are simulated through using Matlab.The resultsshow that the method proposed in this paper is accurate,reliable and can be applied to different fault conditions.