Research On Partial Discharge Of High Voltage Power Cable

As the large application of power cable, the insulation testing of cable become the hot topic of research. The new testing methods of these years have many disadvantages, and any of them are only in the stage of laboratory study. Based on cable's partial discharge(PD) signal, high-frequency electromagnetic coupling method for cable's on-line monitoring has been studied in this paper.The aging of the insulation of cable was closely related to the partial discharge signals's intension. The testing of cable can be achieved by the analysis of local partial discharge signals. The Rogowski coil is chosen as the current transformer which can trap signals, after analysis, the relationship of structure parameters and electrical parameters can be established. Therefore, by means of simulating, the parameter optimization which fits the requirements of testing technique is accomplished. The designs of current transformer are completed by experiments about many different groups of Rogowski coil.As the high-frequency and weakness of partial discharge signals, the design of signal processing circuit and PCB are completed by high Unity Gain Bandwidth Operational Amplifier, and the results are validated by experiments.The math model of cable's equivalent circuit and PD signal are formed.Based on Matlab, simulation circuit are also set up to study the rules of the PD signals'transmission. Many simulation waves and data are obtained, and theoretical interpretations are given.The white noises are added into the simulation waves, to simulate the sophisticated electromagnetic interference in the work environment of power cable. Using wavelet analysis, the partial discharge pulse sequence are broken up, restructured, and signal denoising process, It is found that lifting wavelet and Daubechies can be applied to get good results.