短空气间隙暴雨击穿特性与放电模型研究

发布时间：2018-06-13 15:38

本文选题：暴雨 + 空气间隙　；参考：《重庆大学》2014年博士论文

【摘要】：运行经验表明，暴雨天气严重影响超高压输电线路的安全运行。国内外虽然系统研究了外绝缘的淋雨特性，但极少开展暴雨条件下输电线路外绝缘放电特性的研究。本文通过人工模拟和自然环境试验系统地研究了暴雨条件下棒-板短空气间隙的击穿特性、击穿过程以及击穿模型，论文的主要工作如下：在人工气候室试验研究了0.2~0.7m棒-板短空气间隙暴雨条件下的交、直流击穿特性，分析比较了淋雨强度、水电阻率和环境温度对间隙击穿电压的影响，结果表明，棒-板短空气间隙的交、直流击穿电压均随淋雨强度的增大而线性减小，随环境温度的升高而线性增大；水电阻率对间隙击穿电压的影响较小。在现场暴雨条件下试验研究了10cm棒-板短空气间隙的交、直流击穿特性，结果表明自然降雨条件下棒-板短间隙的交、直流击穿电压均随降雨强度增大而线性减小，降雨强度为0~4.0mm/min时，其降低幅度分别为13.6%和9.3%；提出了暴雨条件下棒-板短空气间隙交流击穿电压的校正公式，试验验证表明本文提出的校正公式计算结果与试验结果的相对误差小于5.7%。试验研究了棒-板短空气间隙棒电极末端有水柱时的交流击穿特性，结果表明，间隙中的水柱会使间隙交流击穿电压降低幅度达到40%；分析得到了水柱流速、水柱直径对间隙交流击穿电压的影响规律，，即棒-板短空气间隙交流击穿电压与水柱流速呈负指数关系，与水柱初始直径呈负线性关系。利用高速摄像机研究了电场对水柱断裂特性的影响，结果表明，电场作用下水柱临界断裂长度、断裂水滴尺寸以及断裂时间都会随外加电压的增大而呈指数规律减小；发现断裂水滴在外加电压较高(40kV以上)时会偏离水柱轴线运动，并指出水柱的螺旋运动是引起该现象的主要原因；得到了水柱临界断裂长度、断裂水滴尺寸、断裂时间与外加电压的数学关系式，分析了水柱流速、直径对其的影响；研究发现断裂水滴数目、水滴径向运动速度与外加电压有关，相同流速下，外加电压越大，断裂水滴数目越多、水滴径向运动速度越大。通过高速摄像机拍摄了棒电极末端有水柱时的间隙击穿图像，提出间隙击穿时，放电电弧首先起始于喷嘴电极，并沿水柱表面发展，在经过离水柱尖端距离最近的水滴后贯穿剩余空气间隙；研究发现间隙击穿前几个毫秒，离水柱尖端距离最近的水滴会在电场作用下朝水柱方向拉长并形成曲率半径很小的“凸起”，由此引发放电朝水滴发展；根据该击穿过程，建立了棒-板短空气间隙击穿模型，该模型由水柱-水滴间隙与水滴-板间隙组成，研究结果表明模型计算结果与试验结果偏差小于12%。
[Abstract]:Operation experience shows that heavy rain weather seriously affects the safe operation of EHV transmission lines. Although the rain characteristics of external insulation are systematically studied at home and abroad, the discharge characteristics of external insulation of transmission lines are seldom studied under heavy rain conditions. In this paper, the breakdown characteristics, breakdown process and breakdown model of rod-plate short air gap under heavy rain are systematically studied by artificial simulation and natural environment test. The main work of this paper is as follows: the characteristics of AC and DC breakdown under the condition of 0.2m rod-plate short air gap rainstorm are studied in an artificial climate chamber, and the rain intensity is analyzed and compared. The effect of water resistivity and ambient temperature on gap breakdown voltage is studied. The results show that the AC and DC breakdown voltage of short air gap decrease linearly with the increase of rain intensity and increase linearly with the increase of ambient temperature. Water resistivity has little effect on gap breakdown voltage. The AC and DC breakdown characteristics of short air gap between 10cm rod and plate were studied under the condition of field rainstorm. The results show that the AC and DC breakdown voltage of short gap between rod and plate decrease linearly with the increase of rainfall intensity under the condition of natural rainfall. When the rainfall intensity is 0~4.0mm/min, the decreasing amplitude is 13.6% and 9.3% respectively, and the correction formula of the AC breakdown voltage of the short air gap between the rod and the plate under heavy rain is put forward. The experimental results show that the relative error between the calculated results and the experimental results is less than 5.7. The characteristics of AC breakdown at the end of rod electrode with short air gap between rod and plate are studied. The results show that the water column in the gap can reduce the gap breakdown voltage to 40 percent, and the flow velocity of water column is obtained. The effect of water column diameter on gap AC breakdown voltage is negative exponential relationship with water column velocity and negative linear relationship with initial diameter of water column. The effect of electric field on the fracture characteristics of water column is studied by using high speed camera. The results show that the critical fracture length of water column, the size of water droplet and the fracture time decrease exponentially with the increase of applied voltage. It is found that the water droplets deviate from the axis of the water column when the applied voltage is higher than 40 kV, and it is pointed out that the spiral motion of the water column is the main cause of this phenomenon, and the critical fracture length of the water column and the size of the water droplet are obtained. The relationship between the breaking time and the applied voltage, the influence of the velocity and diameter of the water column on it is analyzed, it is found that the number of the broken water droplets, the radial velocity of the water droplets and the applied voltage are related to the applied voltage, and the greater the applied voltage is at the same velocity of flow, The more the number of broken water droplets, the larger the radial velocity of water droplets. The gap breakdown image of the rod electrode with water column at the end of the rod electrode was captured by a high speed camera. It was proposed that the discharge arc first started from the nozzle electrode and developed along the water column surface. Through the remaining air gap after passing through the water droplets closest to the tip of the water column; the study found that the gap broke down a few milliseconds before, The water droplets closest to the tip of the water column will elongate towards the water column under the action of an electric field and form a "bulge" with a very small curvature radius, which causes the discharge to develop towards the water droplet. According to the breakdown process, a short air gap breakdown model of the rod plate is established. The model consists of water column-water droplet gap and water drop-plate gap. The results show that the deviation between the calculated results and the experimental results is less than 12.
【学位授予单位】：重庆大学
【学位级别】：博士
【学位授予年份】：2014
【分类号】：TM852;P426.615

【参考文献】