Theoretic Research And Signal Disposal On Partial Discharge Of Power Cable

With the development of modem industry and city, power cable is regarded as an important component for its widely used in power system. Its reliability has direct influence on power system's operation. There are always some cavities, impurities or metal parts for machining technique or raw and processed material in the cable insulation. So partial-discharge(PD) is very easy to happen at cavities or tip of the impurities. The charges caused by PD have close relation with the state of cable insulation. It is indicated that the cable insulation have in bad state if the charges changed. So a nicety detection of PD is the best way to estimate the cable insulation. Now most way of PD detection is off-line measurement, there have no good way to do PD detection on-line.This paper is focused on aspects related to excitation and pick-up of a PD pulse based on some PD detection methods in common use. On-line partial-discharge detection of three-phase belted cable connections results in a number of interpretation differences as compared to off-line measurements where only one phase is energized. The induced currents and charges in the phase conductors and earth screen resulting from the excitation of a PD not only depend on the discharge site, but also become phase-angle dependent. Furthermore, simulations show that the PD distribution itself varies with the amount of eccentricity of the rotating electric field and may differ from the off-line distributions obtained with a linear field.The paper use attenuation exponent function and attenuation concussion function to emulate the partial-discharge signal based on others research. The theoretical analysis and computer simulations are used to verify wavelet's application merits aider presentation wavelet. The result is proved that correlation coefficientρis a good standard to evaluate wavelet used to detect partial-discharge. Choose corresponding wavelet by research character of noise in partial-discharge signal also is proved to be a good way to detect PD signal.