Research On Fault Location Of Transmission Line Based On Improved Hilbert-Huang Transform Based On Traveling Wave Method

It is of great significance for the stability of the power system to quickly and accurately locate the fault point and cut off the faulty line from the power system or restore the line to normal operation after a transmission line fault occurs.The traveling wave method for fault location has been widely used due to its low impact and high accuracy due to the system operation mode and fault conditions.However,there are still some shortcomings in practical applications.This article conducts research on the basis of traveling wave theory,with the aim of making fault location more accurate.The work carried out is as follows:Firstly,aiming at the problem of inaccurate traveling wave velocity,the process of traveling wave propagation is analyzed.Combined with the two-terminal traveling wave method ranging formula,a new ranging formula is established to further improve the accuracy of fault location by recording the correlation between the traveling wave head time points and eliminating the wave velocity.Secondly,the traveling wave signal analysis methods are compared,and the Hilbert Huang transform,which has certain advantages in signal processing,is selected.The problems of envelope fitting,endpoint effect,and modal aliasing in Hilbert Huang transform are improved.Using Akima interpolation for envelope fitting extreme curves improves the impact caused by envelope fitting issues and endpoint effects to a certain extent;At the same time,the complementary set EEMD and CEEMDAN are proposed to process signals,and the analysis and comparison show that the adaptive noise complete set empirical mode decomposition algorithm leaves less residual noise in processing signals,which can improve the modal aliasing problem.Then,aiming at the problem that traveling wave signals may be contaminated by noise during transmission,based on the adaptive noise complete set empirical mode decomposition algorithm,a combination of wavelet threshold denoising method and signal to noise ratio(SNR)and root mean square error(RMS)denoising indicators is proposed.Simulation analysis shows that the adaptive noise complete set empirical mode decomposition combined with wavelet semi soft threshold denoising method is superior to traditional wavelet threshold denoising.Finally,a transmission line fault simulation model is established in the simulation software.Fault location is performed on the transmission line under different conditions.After collecting the fault voltage signal,human simulation is performed to simulate the noise pollution.The noisy signal is subjected to denoising preprocessing and then decoupled to obtain an independent fault traveling wave signal.The improved Hilbert Huang transform is used to process the traveling wave signal,After finding the time point at which the wave head reaches both sides of the line,the fault distance is calculated using the two-terminal traveling wave method formula without wave velocity.The results show that this method is not affected by fault distance,fault type,and transition resistance,and has certain feasibility.