Fault Diagnosis Of Transmission Line Based On Variational Mode Decomposition And Permutation Entropy

The safety and stability of power transmission line is very important for the reliable operation of power system.With the development of intelligent and complex power system,the fault diagnosis and health management of transmission lines are being paid more and more attention.Transmission lines are widely distributed in the power system,the long exposed,often affected by surrounding environment and the change of nature,cause the fault occurs,while the traditional manual transmission line to find fault type has been unable to meet the current requirements of the development of electric power system.Therefore,the fast and reliable transmission line fault diagnosis method based on the transmission line state signal is of great significance to the safe and stable operation of power system and scientific health management.When the transmission line fault occurs,the fault information is hidden in the fault signal.In the existing power system fault signal analysis method,Fourier transform in the analysis of linear and stationary fault signal has a good advantage,but also nonlinear and non local information can effectively smooth fault signal.Wavelet analysis has been on the fault signal analysis can be arbitrary amplification and extraction has the advantages of translation and its characteristics,but the method of selecting different wavelet decomposition scales and lost caused by the fault signal characteristics and fault signal analysis can not reflect the essential characteristics of the signal faults.The empirical mode decomposition method of adaptive signal decomposition,based on the characteristics of the fault signal itself,the adaptive selection of basis function to decompose the signal,automatically determine the signal in different frequency bands of the resolution,to avoid the difficulty of selecting the wavelet function and decomposition scale.However,this method belongs to the recursive mode decomposition.It is easy to appear the characteristic information of the weak signal which is caused by the overlapping of the modal frequency and the noise interference.As the transmission line fault signal for different time,fault point and fault resistance and system under different working conditions,with the mutation and randomicity,and contains a large number of non fundamental frequency transient components in the fault signal,so the above three kinds of traditional methods of transmission line fault signal in the analysis,part of the fault information will be lost fault the signal,and affect the final diagnosis results.In view of the above reasons,this paper proposes a method based on variational mode decomposition and permutation entropy to diagnose the fault of transmission line,so as to solve the problems above.This paper is mainly divided into fault diagnosis of transmission line into two steps:the first step,the variational modal decomposition read a fault signal decomposition of a finite number of intrinsic mode function;the second step,using permutation entropy of the decomposed intrinsic mode function is calculated,by permutation entropy.Then the fault phase of transmission line is judged according to the entropy value.In view of the above algorithms,this paper uses PSCAD and MATLAB to simulate the algorithm.