Simulation Research On Fault Line Detection And Fault Location In Resonant Grounded System Based On Wavelet Analysis

Because of the indeterminate direction and smaller amplitude of residual current of fault point after the compensation of arc suppression coil, the fast and accurate fault line selection has not been well solved yet in resonant grounded system. And it’s also particularly difficult to locate the single-phase grounding fault of resonant grounded system accurately because of the complex structure of distribution network in our country. However, it’s very important to select the fault line and locate fault fast and accurately for meeting the high degree automation of distribution network and improving the quality of power supply further.This thesis has analyzed the transient process of single-phase grounding fault of resonant grounded systematically firstly, And established the simulation model of single-phase grounding fault by ATP-EMTP based on the actual parameters of a practical substation network to simulate various types of single-phase grounding fault, and then Processed and analyzed the simulation data by MATLAB.This thesis presents a comprehensive fault line selection method, which takes the transient information of ground fault into consideration. It takes into account the polar and modulus values of wavelet packet decomposition coefficients of zero-sequence current of fault line and health lines, defined and calculated the fault characteristic value of each line firstly, and got the selection results directly by comparing these values if each line has the same characteristic frequency band. When such bands are different, it could select the fault line adaptively by combining fifth harmonic method with wavelet analysis.We try to apply the double terminal traveling wave fault location method to fault location in distribution network, and have solved a series of technical problems including the different propagation velocity in hybrid feeders, the acquisition of traveling wave signal, and the problem of grounding fault occurs in the branch line. We propose a new single-phase grounding fault location method of the distribution network based on double terminal traveling wave fault location.The results of sets of simulation show that the proposed fault line selection method has a high accuracy and reliability and don’t be affected by fault location, transitional resistor and initial fault angle. Furthermore, it has a higher efficiency in selecting fault line when the network has many hybrid feeders. When the single-phase grounding fault occurs in the pure overhead line and pure cable and pure hybrid feeders, the error of fault location is less than 2% when using the proposed fault location method. And the error is less than 6% when the grounding fault occurs in branch line. Such accuracy can meet the requirement of practical engineering enough.