含电位悬浮导体组合间隙雷电冲击放电特性及击穿机理研究

It is hard to analyze and summary the breakdown mechanism of combined gap containing potential-floating conductor due to the complicated influence factor. In this project, the lightning impulse of representative rod-plate-rod model which contains potential-floating conductor is studied. The detailed content is shown below.(1) Based on the theoretical analysis of lighting impulse procedure of combined gap containing potential-floating conductor, we can determine the value range of experimental parameters, build up experiment and observation platform, and design the experimental analysis method.（2）Based on the single factor and orthogonal experiments, we can choose and quantize the influence factor of lightning impulse of rod-plate-rod model which contains potential-floating conductor. Based on the major factor and discipline, the breakdown mechanism can be analyzed according to the observation on breakdown voltage, breakdown time, breakdown path, and pre-discharge current.（3）Based on the steamer theory, the simulation of the gap lightning impulse is separated into several steps. The transient potential and path parameters of potential-floating conductor are determined by electric field calculation and experimental results simultaneously. Also the simulation model of the combine gap lightning impulse discharge process which contains potential-floating conductor can be built accordingly. The project can reveal the mechanism of combined gap lightning impulse discharge process which contains potential-floating conductor. The expected results can provide both theoretical direction and experimental evidence for the design of combined gap.

工程中含电位悬浮导体组合间隙的击穿过程影响因素复杂，不易总结规律、分析机理。本项目以含电位悬浮金属板的棒-板-棒典型间隙为代表对象，研究其雷电冲击击穿特性，内容包括：（1）基于含电位悬浮导体组合间隙雷电冲击放电过程的理论分析，确定影响间隙击穿特性的各条件参量的取值范围，构建试验及观测平台，设计试验研究方案；（2）通过单因素对比试验和正交试验对影响棒-板-棒组合间隙雷电冲击放电特性的因素进行遴选和量化，以主要因素及规律为基础，以击穿电压、击穿时间、击穿通道及预放电电流的观测结果为依据进行击穿机理分析；（3）基于流注理论，将间隙击穿过程分阶段进行模拟，结合电场计算及试验观测结果确定悬浮导体瞬时电位和流注通道参数，建立含电位悬浮导体组合间隙雷电冲击击穿过程仿真模型。拟通过项目研究揭示含电位悬浮导体组合间隙雷电冲击击穿机理，预期成果可为组合间隙的设计及应用提供理论指导和试验依据。

在电力系统中，由于自然环境或人为操作等原因，空气绝缘间隙中有时会出现电位悬浮导体，共同构成组合间隙，其放电行为更加复杂，放电特性难以总结。本项目设计了间隙放电发展过程同步综合观测平台，实现组合间隙放电电流与高速光学影像的同步观测，针对棒-金属板-棒组合间隙结构，开展了不同电压极性、间隙长度、金属板位置等条件下的组合间隙放电试验，对组合间隙放电特性进行分析研究。.本项目提出了以无感电阻为传感器的电流测量方案和以高速摄影仪为主要部件的间隙放电发展过程同步综合观测平台。制作了50Ω的无感电阻传感器，采用鼠笼式并联结构提高其通流能力；选取带宽200MHz的采集卡作为采集核心部件，设计了同步通信方案与屏蔽结构，制作了放电电流测量系统；针对放电过程的光学特性，选取高速摄影仪记录先导放电发展过程，同时使用单反相机对放电路径进行拍摄，搭建起间隙放电发展过程同步观测平台。.本项目开展不同间隙长度下的组合间隙放电试验，以金属悬浮电位位置为主要变量，研究金属悬浮电位导体对组合间隙冲击放电特性的影响。发现组合间隙整体击穿电压略高于相同长度的棒-棒间隙，金属板在不同位置时，其击穿电压差异较大。在正极性电压下，金属板距离高压极较近时，低压棒-板间隙会出现放电与板边缘相连的现象，而负极性时正好相反。当金属板距离一侧棒电极较近时，组合间隙整体击穿之前，相对较短的棒-板间隙会有多次间歇击穿现象，每次持续时间在1μs以内。.本项目分析认为悬浮电位导体能提升高压极头部场强，促进其起晕；单侧棒-板间隙多次击穿后，金属板电荷累积会削弱击穿侧棒-板间隙场强，抑制其再次击穿，但能提升未击穿侧棒极头部场强，促进棒电极产生电晕与流注；放电路径与板边缘相连主要由单侧棒-板间隙击穿后金属板边缘场强大幅提升导致。本项目研究结果，能够为电力系统间隙设计提供相应的理论指导。