Directivity Evaluation Of Transformer Partial Discharge Ultrasonic Array Sensor

Power transformer is the key equipment of power system,and its operation reliability directly affects the security of the whole power system.However,partial discharge is one of the main causes of transformer insulation damage.Therefore,partial discharge detection has become a critical project of transformer insulation mechanism research and quality control,it is and an important basis for transformer's condition monitoring and maintenance.The ultrasonic array detection method of partial discharge(PD)is a new method which combines the array sensor and array signal processing technology(ASPT)to detect PD ultrasonic signal.Among them,the partial discharge ultrasonic array sensor with good performance and appropriate structure is the premise and key to achieve effective detection.This paper is supported by National Natural Science Foundation of China(51307060)"Research on Partial Discharge Fault Location Method Based on New Built-in Fiber F-P Sensor" emphatically to carry out the research on the pointing performance and direction-finding performance of the PD ultrasonic array sensor.The main contents are as follows:A pointing performance evaluation method for a partial discharge ultrasonic array sensor was studied.Firstly,a four-element cross-shaped array,a diamond-shaped array,and a regular tetrahedral array were developed basing on the Extrinsic Fabry-Perot Interferometric(EFPI)ultrasonic sensor.Based on the basic theory of array directivity,the directional accuracy and the main beam width were selected as the characteristic parameters.And then the spatial multi-angle directivity of the above three array sensors were explored.The results show that the directivity of the cross-shaped and diamond-shaped arrays deteriorates with the increase of the beam deflection angle,while the direct tetrahedral array has better directivity to the spatial multi-angle than the cross-shaped array and the diamond array.The DOA estimation principle and Multi-signal classification(MUSIC)of EFPI sensor array signals are studied.Then,the partial discharge detection simulation,experimental model in transformer oil and 4-channel synchronous data acquisition device test platform were built.What's more,the direction-finding study of spatial multi-angle partial discharge was carried out.The results show that the different sensor arrays have the same change of direction-finding accuracy and directivity for the source in different directions.Compared with the cross-shaped and diamond-shaped planar arrays,the regular tetrahedral EFPI fiber-optic ultrasonic array sensor has a good space full-angle partial discharge.Direction finding capability.Compared with the cross-shaped and diamond-shaped planar array,the regular tetrahedral EFPI fiber ultrasonic array sensor has a good direction-finding capability of space full-angle's partial discharge.Aiming at the actual transformer winding structure,three dimensional diamond array sensor with different structures was developed based on the planar diamond array sensor.Then the spatial directivity of the array was explored,and the direction-finding of space full-angle's partial discharge by simulation and experiment is carried out to search an optimal array.The research results further validate the feasibility of the performance evaluation method of the partial discharge ultrasonic array sensor,and we obtain the intrinsic relationship between the stereoscopic form of the array and its spatial pointing performance and direction-finding performance,which is used to guide the design of the stereo array sensor.