Research On Transmission Line Fault Location Based On TT Transform

With the increasing voltage level,operating capacity and volume scale of electric networks in our country,transmission lines are facing more complex environment and operating conditions.The transmission network connects the power generation side and the power supply side,so that the fault can be removed quickly and the power supply can be restored,which is conducive to reducing the economic loss and improving the operation stability.Therefore,the research on fault location is of great significance.Firstly,the basic concept of traveling wave is introduced,and the generation principle and propagation process of traveling wave are introduced in detail.In view of the coupling phenomenon between the phases of three-phase transmission lines,after analyzing and comparing the existing phase-mode transformation methods,this paper proposes to use Kellenbell transformation matrix to decouple them,and introduces in detail the commonly used traveling wave ranging schemes,and analyzes and compares their respective advantages and disadvantages.Secondly,Fourier transform,short-time Fourier transform and wavelet transform,the time-frequency domain analysis methods of transient traveling wave signal are introduced.Through the combination of principle analysis and simulation,the shortcomings and defects in the extraction of transient traveling wave head are pointed out respectively.Then,TT transform is proposed to analyze the traveling wave,and the principle and properties of TT transform are analyzed.A simulation example is given to verify the applicability of this method in the field of analyzing abrupt change signals.Then,aiming at the fault location of single-ended transmission lines,the TT transform combined with BP neural network is proposed.By analyzing the motion process of traveling wave at different fault locations,the sample data set required for BP neural network training is constructed by selecting the time value and the polarity of the wave head,and the BP neural network is optimized by genetic algorithm.Further improve the ranging accuracy and convergence speed.For T-type transmission lines,based on the twoterminal ranging method,a new method is proposed which only needs to measure the arrival time value of the wave head by TT transformation without introducing the wave velocity to realize fault branch identification and location.Finally,in Matlab/simulink simulation verification,the experimental results show that the proposed method,ranging accuracy is high,and is not affected by the fault type,transition resistance and wave speed variables.