Research On Fault Location Algroithm Of Transmission Lines Based On Compressed Sensing And Traveling Wave Natural Frequency

The transmission line is the most fault in the power system.If the fault location is determined in time,accurately and reliably,it can bring great economic benefit.Therefore,the fault location is of great significance to the safe and stable operation of the power system.As a new information acquisition guidance theory,compressed sensing has brought a revolutionary breakthrough for data acquisition technology,and has a wide application prospect in power system signal analysis and detection.In order to solve the problem that the positioning accuracy of the existing fault location method is often influenced by the factors such as the transition resistance and the change of the system parameters,it is difficult to accurately identify the wave head and calculate the corresponding traveling wave velocity accurately.This paper applies the compressed sensing theory to the fault location of the transmission line.Most of the fault methods for AC transmission lines only extract a single natural frequency value,which are greatly influenced by noise,line discontinuity,harmonic interference and so on,thus affecting the positioning effect.In this paper,a fault location method based on compressed sensing to estimate the natural frequency of traveling wave is proposed,which can accurately estimate the natural frequency of multiple traveling waves,and has a high accuracy of fault location.The design of over complete dictionary is optimized through the frequency domain characteristics of the fault traveling wave signal of the AC system,so that the traveling wave signal can be effectively expressed sparsely.When the fault location is located,the frequency boundary of the fault traveling wave signal is first determined by the wavelet modulus maxima method,and the FIR filter is used to filter the low-frequency interference components,and then it can be transformed into the frequency domain to make it sparse representation in the over-complete dictionary.On this basis,this paper uses the improved orthogonal matching pursuit algorithm to reconstruct the frequency domain signal of the fault traveling wave,and accurately identifies the multiple natural frequency values of the traveling wave signal,and finally realizes the accurate fault location by combining the reflection angle and the wave speed.Besides,this paper applies the multiple natural frequency fault location algorithm based on compressed sensing to the fault location of DC line and further improves it.The voltage source converter based on high voltage direct current(VSC-HVDC)system is a new type of transmission system,which has a broad application prospect.Therefore,the common faults are simulated on the basis of the VSC-HVDC simulation model.The frequency domain representation of the VSC-HVDC system is more acute than that of the AC system.By analyzing the frequency domain characteristics of the fault wave,a new over-complete dictionary dictionary of the DC system is designed.Then the Dice coefficient atom matching criterion and the Fourier transform are used to improve the regularized orthogonal matching pursuit algorithm.It is better to reconstruct the original signal,improve the ability to identify multiple natural frequencies,and achieve precise fault location for HVDC transmission lines.Finally,the analysis of the different faults of high voltage AC transmission system and HVDC system is carried out to test the influence of these parameters.The simulation results prove that the fault location algorithm based on compression perception and traveling wave natural frequency DC fault location algorithm can effectively locate the fault of AC line and DC line,and the method of this paper is illustrated.It has good fault location reliability and adaptability,and its location accuracy in different situations is basically over 99.5%.