The Acoustic Performance Evaluation And Sparse Design Of Partial Discharge Ultrasonic Array Sensors

The detection method of partial discharge (PD) using ultrasonic array signals is a new method that applies the array sensor and array signal process technique (ASPT) to the PD detection. The ultrasonic array sensor with high quality and reasonable dimension is the key of the PD detection in electrical equipment. However, the research on the acoustic performance of PD ultrasonic array sensor is mainly just qualitative analysis, not developing the quantitive research systematically and scientifically yet.This paper is supported by National Natural Science Foundation of China(51307060)"Research on the extraction strategy of partial discharge ultrasonic array signals", Natural Science Foundation of Hebei Province in China (2010001703)"Research on the location of partial discharge in power transformer based on ultrasonic array sensors" and the Fundamental Research Funds for the Central Universities (09MG09)"Research on the location of partial discharge in transformer using ultrasonic phased array", emphatically to carry out the research on evaluating the PD ultrasonic array sensor's acoustic performance and its sparse design. The main contents are as follows:The square and circular ultrasonic array sensors which are suitable for partial discharge detection and a complete experimental system for PD location are developed. First, we study the parameters of the array element such as its material, central frequency, thickness and the radius, and then we design the structural model of the single array element and the models of PD square and circular ultrasonic array sensors. Second, the material object is manufactured. Third, the testing platform of the array sensor is put up to proceeding the sensitivity testing. The results show that the PD ultrasonic array sensor has good frequency response characteristic and consistency. Finally, a complete experimental system of the location of partial discharge using ultrasonic array sensor is established. The system contains the ultrasonic array sensor, portable detection system of partial discharge and the software system of PD location, which is the foundation for the follow-up study.A novel effective method to locate the PD source using ultrasonic array sensor is proposed. First, the de-noising, focusing, direction-finding and accurate locating of the PD ultrasonic array signals are realized by using FastICA(Fast Independent Component Analysis^TLS(Total Least Square)^improved FastDOA(Fast Direction of Arrival) and the principal of geometrical location of bearing line's center of minimal inscribed circle respectively. Then the simulation and experimental results verify the effectiveness and superiority of it.A quantitive evaluation method to evaluate the PD ultrasonic array sensor's acoustic performance is proposed. First, as for square and circular PD ultrasonic array sensors, their directivity function is derived based on Huygens' Principle. Second, the three-dimensional directivity pattern is analyzed qualitatively, which verifies the necessarity of the quantitive evaluation of the acoustic performance. Then, the directive accuracy and the maximum amplitude of side lobe are selected as indexes to establishing the quantitive evaluation model of PD ultrasonic array sensor's acoustic performance. Finally, the variation among the array sensor's acoustic performance, array structure and the number of array is studied by simulation and experiments, which can verify the correctness of the evaluation method proposed in this paper.A sparse design method of PD ultrasonic array sensor based on the combination of the acoustic performance evaluation and intelligent search algorithm is proposed. First, the array sensors' directivity function considering sparse distribution are derived through the example of the square and circular PD ultrasonic array sensors with9and36array elements, through these functions, we can obtain the optimal sparse distribution structure of the array sensors under different degree of sparse with the goal of the optimal evaluation value of acoustic performance and the chaotic monkey algorithm. The simulation and experimental results show that the acoustic performance of the circular PD ultrasonic array sensor in optimal sparse structure is superior to that of square in certain sparseness, while the full-rank circular array has the best acoustic performance when the element's number is the same.