Research On Partial Discharge Location In Power Transformer Based On Ultrasonic Sparse Array

The research of partial discharge(PD) location testing is the key project of quality control and insulation mechanism study of transformer. However, fixed array element spacing, to some extent, can’t meet the requirements of the broadband ultrasonic signals generated by transformer PD and measurement error exists as a result. When the array element spacing is more than half the ultrasonic wavelength, the problems of angle ambiguity and false peaks occurs during array calculation. Therefore, research on ultrasonic sparse array positioning of transformer PD has important theoretical and practical significance.In this paper, a MVDR beamforming based false peak suppression algorithm and sparse optimization of ultrasonic receiver array based on simulated annealing algorithm are presented. According to the characteristics of the broadband array signal of transformer PD, phenomenon of larger grating lobe occurring in the array signal after sparse sensor array is analyzed and then a MVDR beamforming based false peak suppression algorithm is proposed. On this basis.twin matrix decomposition based interpolation MVDR algorithm is presented. Large number of simulation studies show that the algorithm presents a better suppression for gate valve of transformer PD signal received in linear sparse array:in the ultrasound transducer sparse array optimization process, with the target of minimum sidelobe energy, on conditions that the array aperture is set to ensure the minimum spacing between array elements is greater than the sparse level, simulated annealing algorithm is used for global search for array degradation configuration and sparse optimization algorithm of ultrasonic receiver array based on simulated annealing algorithm is presented. Through simulation studies, the main lobe of optimized sparse array received by simulated annealing algorithm is provided with basically the same line width with the traditional spaced linear matrix and the grating lobe caused by sparse array is also suppressed.A system of ultrasonic array experimental for PD location was built. By using MVDR beamforming based false peak suppression algorithm together with algorithm of global search for intelligent positioning, the suppression algorithm for false peak of PD sparse array is verified through numbers of experiment study.