Research On Dual Partial Discharge Source Location Of Transformer Based On EFPI Sensor Array

Power transformer is one of the most critical core equipment of energy exchange in power grid system.Its safe and stable operation is directly related to the reliability of power grid.At present.in order to meet the requirements of high voltage level in power energy transmission,the voltage level and power conversion capacity of transformer are also increased accordingly.Therefore,transformer fault diagnosis and online monitoring become an important strategy to ensure the safe and economic operation of power system.PD ultrasonic array detection is a new method which combines array sensor with array signal processing technology.The PD ultrasonic array sensor with good performance and reasonable structure is needed to detect and locate the ultrasonic signal of double partial discharge sources in transformer.In this paper,based on the EFPI sensor,the propagation law of PD ultrasonic signal in transformer is explored deeply,and the tetrahedral sensor array is made,which is applied to the detection and location of dual PD ultrasonic signal in transformer for the first time.Multiple signal classification(Music)algorithm is used to get the direction of arrival of the local amplifier,and the method of direction finding cross location is used to solve the location problem of the dual local amplifier.Through the COMSOL finite element simulation analysis software,the localization of the aual partial discharge source in the oil tank is simulated.Combined with the research on the directivity of the sensor array,the tetrahedral array with small overall DF error and stable performance is selected,which is more suitable for the direction finding cross localization of the dual partial discharge source.Through the PD optical fiber sensor detection test platform,three different PD models of the dual sound source direction finding experiments are carried out in the oil,and the PD detection platform composed of Marx generator and improved tip discharge tube model is selected to detect and locate the dual PD signal in the transformer.Several partial discharge sources are arranged between the turns of the high and low voltage windings of the transformer,and the simulation and experimental research are carried out respectively.The direction finding and cross positioning of the experimental data are carried out by music algorithm.Considering the complex coil structure inside the transformer winding,the complex cepstrum de reverberation algorithm is introduced to study the detection and location of double partial discharge sources inside the transformer winding.The experimental results show that the algorithm based on the minimum phase decomposition of complex cepstrum can effectively improve the detection and positioning accuracy of dual partial discharge sources in high and low voltage windings of transformers.