【作者】 张连星；

【导师】 郑殿春；

【作者基本信息】 哈尔滨理工大学 ， 高电压与绝缘技术， 2011， 硕士

【摘要】 局部放电是高压电器设备绝缘劣化的主要原因,又是评定其绝缘老化程度的重要参数,存在于绝缘中的气泡或气穴是触发局部放电的主要根源。因此,短气隙放电特性的研究对高压电器设备在线监测和故障诊断具有实际意义。为了研究电力设备绝缘结构短气隙放电,并深入理解绝缘结构短气隙放电过程中的动力学行为,研究交流电压下介质表面积聚电荷对短间隙气体放电的影响,本文建立了一维自洽流体力学的气体放电模型,主要包括电子和离子的连续性方程和动量方程,同时耦合泊松方程。数值仿真的简化物理模型是由电极覆盖的平行圆板电极和短气隙构成。计算结果显示,当气隙中电场超过其击穿阈值时,形成放电电流脉冲,也就是气体中空间电荷运动形成电子雪崩放电,同时,获得了大气压下电子雪崩放电过程中气体间隙电场,电子密度,离子密度的时空分布。仿真结果表明,短气隙、电压幅值和驱动频率不仅会影响气隙放电电流脉冲的幅值,还会促使脉冲数目发生变化;短气隙放电具有较明显的混沌特征;介质表面积聚电荷是形成多脉冲气隙放电的根本原因。本文针对短气隙放电设计了5种实验电极模型,用于模拟不同气隙下电场分布。采集短气隙放电信号,利用连续小波进行处理,获取放电电流脉冲的时频特征,结果显示气隙放电信号的频带能量可以作为模式识别的输入特征向量。更多还原

【Abstract】 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.更多还原