Cable Multi-source PD Detection And Location Based On Oscillating Wave

Partial discharge(PD)is the early sign of the cable fault,in the PD prone period,detecting the level of cable insulation PD through efficient and effective means,and judging the cable insulation health status through test result,meanwhile,using the cable PD signals to determinate the PD location combining with the traveling wave ranging method,thus taking appropriate measures,have important significance on the safe operation of the cable and the grid.The Oscillating Wave Test System(OWTS)is a new method in recent years,and has been unanimously promoted.In this paper,based on the OWTS,the structure,the parameter settings and the detail working principle of OWTS are further analyzed,meanwhile,with the Simulink,OWTS model is built and the process of the partial discharge(PD)signals occurring and detection is simulated;On the base of simulation,a small OWTS is successfully developed,by setting cable point defects artificially,the system was tested and the result shows that the developed system successfully simulates the working process of OWTS and collects the PD signals in accordance with point discharge characteristics,which proves the effectiveness of the developed system and lays a foundation for the further research work.Based on the PD signals obtained by OWTS,which contain a lot of white noise and narrow-band interference,considering the existing white noise denoising algorithm has been more mature,a PD narrow-band interference suppression algorithm combined with frequency-domain estimation and time-domain reconstruction is proposed in this paper only for PD narrow-band interference suppression.According to the distribution differences of PD signal and narrow-band interference in time-domain and frequency-domain,the algorithm realizes the narrow-band interference number determination and the narrow-band frequency rough estimation by analyzing the similarity of each segmented signal spectrum after segmenting the sampling data.Afterwards,the algorithm uses frequency-domain interpolation to realize the precise estimation of the narrow-band frequency and reconstructs the narrow-band interference combining the Fourier series expansion,finally suppresses narrow-band interference through the subtraction with the original signal.Through algorithm contrast for the simulation and the measured data,the advantage of the proposed algorithm in improving precision for the narrow-band interference parameter estimation and signal reconstruction is validated,as well as the good effect in narrow-band suppression in different working conditions.Meanwhile,the proposed algorithm's stability against the white noise is validated so that it can meet the narrow-band suppression application demand in complex scene working conditions.In the process of PD source location through using the PD signals obtained by OWTS,in order to reduce the influence of noise interference and reflection interference and realize multiple PD sources' location,a multi-source PD location algorithm which is based on the PD matching pair recognition is put forward to improve the locating accuracy.The algorithm uses the PD signal amplitude mutation and the propagation characteristics in cable to identify the PD matching pair,locates the multiple PD sources based on the identify results,and corrects the location results through the DBSCAN clustering method to realize the accurate location of multiple PD sources.The simulation results show that,the multi-source PD location algorithm can effectively identify the PD matching pair and accurately estimate the numbers and location of PD sources in different SNR conditions.Meanwhile,because multiple sets of PD matching pairs are used for location,the location accuracy is higher than that of using one set of PD matching signals.Theoretical research and simulation results show that,the proposed method of the cable multi-Source PD detection and location based on oscillating wave has achieved a certain effect on the detection,denoising and location of the cable PD signal and provides an important security guarantee.