Analysis Of The Gas Discharge Process In The Short-gap At Atmospheric Pressure

The gas discharge in the short-gap is not only the main cause of insulation degradation in high voltage electric apparatues, but also it is a crucial parameter for evaluating insulation ageing, thus the researching on the gas discharge in the short-gap has important practical significance for on-line monitoring and fault diagnosis of high voltage power equipment.With the purpose of studying partial discharge in the short-gap of the insulating coordination and deeply understanding kinetic behavior of gas discharge in gas-dielectric insulation, the one dimensional and self-consistent fluid model of the gas discharge was established based on the electron and ion continuity and momentum transfer equations coupled to Poisson's equation, then the micro-discharge evolution of the short-gap and its influence of the surface charges depositing on dielectrics applied alternating voltage were analyzed and demonstrated in detail. The models of mathematical simulation, representing a plane-parallel electrode arrangement covered with solid dielectric and comprising an short gas-gap, were made up, then the results were obtained for the case when the applied field in the gas exceeds its breakdown threshold and discharge current pulses can be formed, i.e. charge transfer in the gas phase takes place in the form of an electron avalanche discharge, simultaneously, the facts were found that the temporal and spatial distributions of the electric field, electron density and the ion density obtained in the electron avalanche discharge at atmospheric pressure. Simulation results show that the gap dimensions, applied voltage amplitudes and frequencies can also influence on the numbers and the amplitudes of current pulses. Furthermore, the characteristic of chaos that gas discharge is obvious in the gas discharge with short gas-gap, surface charge accumulation on dielectrics in opposite polarity, forming reversed field relatived to the applied field, is the essential reason.The five models of short gas-gap discharge for different electric field are designed and made, and then experiment data of gas gap discharge are collected. In signal analysis, the continuous wavelet is always used for signal decomposition, which is an effective time-frequency analysis method for observing the time-frequency property of discharge current in the short gas-gap. The consequence is excting satisfaction, which extract frequency energy of discharge current and take as features for pattem recognition.