Study On Partial Discharge Ultrasonic Array Location In Oil Based On Sparse Representation

Electrical equipment partial discharge detection is important for the safe operation of power system.The ultrasonic signal generated by the partial discharge(PD)in the oil is a broadband signal.But at the moment,most of the array signal processing methods are used for narrow-band signal,and the effect of some methods for processing wideband signals are not satisfactory.Therefore,it is necessary to find new broadband signal processing methods,to improve detection ability of the PD source.This paper is supported by National Natural Science Foundation of China(51307060)“Research on the extraction strategy of partial discharge ultrasonic array signals”,Fundamental Research Funds for the Central Universities(2014MS84)“Research on the acoustic performance and structure optimization of PD ultrasonic array sensor” and New Energy Power Systems State Key Laboratory Fund(LAPS14011)“Research on Multiple Partial Discharge Location by Ultrasonic Array”.The application of signal sparse representation theory in the ultrasonic array detection of partial discharge is studied.The main contents are as follows:Firstly,the direction of arrival(DOA)estimation method based on received data sparse representation is researched,and a step by step over complete dictionary that can improve the computational speed is set up to deal with the variables to be decomposed.The simulation results show that the step by step over complete dictionary can improve the operation speed and save the time of signal processing.The DOA estimation method based on received data sparse representation can realize the accurate direction finding of PD broadband signal for three kinds of full array ultrasonic array sensor and their sparse structure,and thus improve the following positioning accuracy of the three array localization method.And then,the DOA estimation method based on characteristic vector sparse representation is proposed.Firstly,the received broadband PD signal is focused on a single frequency covariance matrix.Then,the characteristic vector of the maximum eigenvalue is obtained by decomposing the covariance matrix,and the vector is used as the variable to be decomposed.This method can further reduce the noise interference.The simulation results show that this direction finding method is feasible for three kinds of full array ultrasonic array sensor and their sparse structure,and thus improve the following positioning accuracy of the three array localization method.Finally,the experimental platform is set up,and the method based on signal sparse representation is used to deal with the measured PD signal in the laboratory.Experimental results verify the two direction finding methods based on received data sparse representation and based on characteristic vector sparse representation are feasible both for the full array and sparse array,which can achieve accurate estimation of direction of arrival and improve the following positioning accuracy.This can provide important guidance information for the equipment maintenance in the practical application.