Research On Partial Discharge Detection Method Under The High Frequency And Pulse Electrical Stress

With the development of the power electronics technology and device in the field of high-voltage, high-voltage smart devices such as converter valves and the saturable reactors, power electronic transformers are widely used. However, the harsh and complexity and complexity working conditions lead to the premature failure of the operation equipment design. Partial discharge detection is one of the effective means of assessing the insulation state methods, but when facing more high pulse repetition rate and steep rising/falling edge, the conventional partial discharge detection method has failed. Therefore, in order to study the partial discharge behavior and factors smart devices lay the foundation for state assessment test method, the need for PD detection methods applying to high frequency and pulse voltage could be urgent.In this paper, the PD test platform has been built, which including the current sensor, coupling capacitors, oscilloscopes and so on in order to raise the noise ratio and sensitivity. Then wavelet thresholding method based on the empirical mode decomposition (EMD) has been used to reduce noise and obtain the Effective waveform. By combining the above methods, PD information such as discharge capacity, frequency and phase could be extracted.PD capacity is one of the most important parameters in the PD detection. In this paper, the deconvolution algorithm based on the incremental Wiener filter was used reconstruct the input PD waveform in order to solve the frequency limitation problems,which achieving the purpose of PD calibration.Based on the above, a PD detection systems by using Labview software had been developed, which not only making the real-time data acquisition and processing more convenient, but also is to facilitate analysis the quantities and characteristics of the PD under high frequency and pulse electric stress.To analog the actual operating conditions of high frequency power electronic transformers and saturable reactors, the typical electrode and class saturated reactor electrode were designed. Based on the PD experimental data and theoretical analysis, the influence of frequency and steep rising/falling edge on the characteristics of the PD under high frequency and pulse electric stress had been explored. Then the space charge accumulation effect to the experimental phenomena and premature insulation damage phenomenon was analyzed and discussed. In addition, by using electron microscope scanning (SEM) methods to observe the polyimide insulation surface breakdown point location near the micro degradation, we pointed out that the high rate of voltage rise and rapid reversal is the primary factor causing damage to insulation, which fit with the experimental results above.In this paper, the PD detection and experimental data provide important theoretical and practical significance to life-cycle management and Insulation condition assessment of the smart devices such as PET and saturable reactors. What’s more, it provided certain guiding value on the safety stability of the HVDC transmission system and the existing equipment inspection...