工频电压下片状自由金属微粒带电特性与运动规律研究

Study on the Charge Characteristics and Movement Pattern of Lamellar Particles Under Power Frequency Voltage

GIS/GIL因安装、运输等环节会不可避免地产生多样性的金属微粒,而片状金属微粒因其"潜伏性"较难检出,从而威胁GIS/GIL的绝缘性能。采用数值计算结合实验方式开展了工频电压下片状金属微粒起跳与运动规律研究。片状金属微粒采用旋转椭球体模型进行等效,并通过理论推导获得片状金属微粒的带电量与临界起跳场强。搭建工频电压下片状金属微粒运动观测平台。采用高速相机观测其起跳和运动行为,并与数值计算结果进行对比分析。结果表明:片状金属微粒起跳场强与厚度的1/2次方近似呈正比关系,而随微粒半径增大呈现出微弱的上升趋势。密度较大的片状金属钢微粒竖起后,存在原地旋转与沿地电极表面来回滚动两种运动模式,并在微粒底部与电极间隙伴有微弱的局部放电;密度较小的片状金属铝微粒竖立后,在电极间隙内发生剧烈地上下跳动。

GIS/GIL would inevitably produce a variety of metal particles during installation and transportation, and lamellar particles are difficult to be detected due to their "latency", which greatly threatens the insulation performance of GIS/GIL. This study used numerical calculation and experimental methods to research the lift-off and movement law of lamellar particles under power frequency voltage. The lamellar particles were equivalent using a spheroid model, and the charge amount and the critical take-off electric field strength of the lamellar particles were derived theoretically. An platform observing the movement of the lamellar particles under power frequency voltage was built. A high-speed camera was employed to observe the lift-off and movement process of lamellar particles, which were further analyzed and compared with the numerical calculation results. The results show that the lift-off electric field strength of lamellar particles is approximately proportional to one-half of the thickness, and shows a slight upward trend as the particle radius increases. After the stainless lamellar particles are upped, there are two patterns of particle movements: rotating on the spot or rolling back and forth along the surface of the ground electrode. Simultaneously, there is a weak partial discharge between the bottom of the particle and the ground electrode. After the aluminum lamellar particles are upped, they jump up and down violently and frequently in the electrode gap.