雾中输电线路绝缘子交流放电特性及闪络过程研究

发布时间：2018-09-06 07:58

【摘要】：随着我国经济的迅速发展，大气环境不断恶化，近些年来国内各地不断出现的大雾天气，严重威胁到电力系统的安全稳定运行，雾的物理化学特征及雾的状态等对输电线路绝缘子雾闪放电特性及闪络过程有着重要的影响。目前，国内外研究学者对其研究相对较少。基于以往的研究成果及存在的问题，采用试验研究和理论分析相结合的方式，首先在重庆大学湖南省怀化市雪峰山自然覆冰试验站对自然雾的物理化学特征进行了测量分析；然后研究了雾中绝缘子表面湿润受潮过程及其影响因素，最后选取典型的XP-160和LXY4-160悬式绝缘子为试验研究对象，研究雾中绝缘子交流放电特性。通过分析得到以下结论： (1)自然雾中绝缘子表面湿润受潮包括水分子冷凝过程和绝缘子表面雾水水滴碰撞过程。水分子冷凝过程是亚稳态的过饱和水蒸汽自发转变为稳态的液态水或晶体的过程；通过建模仿真分析了绝缘子表面的水滴碰撞特性，分析了风速和水滴直径对水滴碰撞系数的影响，得出水滴碰撞系数随风速和水滴直径的增大而增大。蒸汽雾中，绝缘子表面湿润过程主要是冷凝作用；超声波冷雾中，绝缘子表面湿润过程主要受到雾水水滴碰撞绝缘子表面的影响。 (2)清洁绝缘子雾闪电压随着雾水电导率的增加而逐渐下降，单片清洁XP-160绝缘子雾闪电压U50与雾水电导率γ20满足如U50K a20K a20的幂指数形式，其中K=134.65，a=0.158，相关系数R20.97。通过对计算值和试验结果的对比，两者相对误差在5%以内，因此可认为推导拟合的关系式是可行的。 (3)污秽绝缘子雾闪电压U50随着雾水电导率γ20的增加而逐渐下降，且具有饱和趋势。为研究雾水电导率对污秽绝缘子雾闪电压的影响特性，，定义附加盐密，污秽绝缘子雾闪电压可表示为U50A S a，式中为附加盐密，mg/cm2。附加盐密与雾水电导率近似成线性关系，可表示成b20c。通过对计算值和试验结果的对比，两者相对误差在7%以内，因此可认为该数学模型是可行的。 (4)雾中绝缘子交流雾闪电压随着雾水温度的升高而逐渐减小。其原因主要是温度升高，能增大溶液的溶解度，使更多的NaCl溶解；能降低溶液的粘度，使得溶液中离子运动速度的增大。 (5)气流的吹弧效应对自然雾中绝缘子放电电弧的形态起主导作用，在局部电弧形成直至闪络过程中，风速为0~5m时，气流对自然雾中绝缘子放电电弧形态的影响较小，可以忽略；风速为10~15m时，气流对自然雾中绝缘子放电电弧形态的影响较大，主要表现为电弧直径的减小，放电电弧成为多分支体。
[Abstract]:With the rapid development of China's economy, the atmospheric environment is getting worse and worse. In recent years, the foggy weather in various parts of the country has seriously threatened the safe and stable operation of the power system. The physical and chemical characteristics of fog and the state of fog have an important influence on the flashover discharge characteristics and flashover process of insulators on transmission lines. At present, the domestic and foreign research scholars to its research is relatively few. Based on the previous research results and existing problems, the physical and chemical characteristics of natural fog were measured and analyzed at Xuefeng Mountain Natural Ice Test Station of Huai Hua City, Hunan Province, Chongqing University by combining experimental research with theoretical analysis. Then, the wetting process of insulator surface in fog and its influencing factors are studied. Finally, typical XP-160 and LXY4-160 suspended insulators are selected as experimental objects to study the AC discharge characteristics of insulators in fog. The main conclusions are as follows: (1) wetting of insulator surface in natural fog includes condensation process of water molecule and collision process of water droplet on insulator surface. The condensation process of water molecules is the process of spontaneous transformation of supersaturated water vapor from metastable state to steady state liquid water or crystal. The characteristics of water droplet collision on insulator surface are analyzed by modeling and simulation. The influence of wind speed and droplet diameter on the impact coefficient of water droplet is analyzed. It is concluded that the impact coefficient of water droplet increases with the increase of wind speed and droplet diameter. In steam fog, the process of wetting insulator surface is mainly condensation; in ultrasonic cold fog, The wetting process of insulator surface is mainly affected by the impact of fog water droplets on the insulator surface. (2) the lightning pressure of clean insulator mist decreases with the increase of fog conductivity. The lightning pressure U50 of monolithic clean XP-160 insulator and the conductivity 纬 20 of foggy water satisfy the power exponent form of U50Ka20Ka20, in which the correlation coefficient is R20.97. By comparing the calculated values with the experimental results, the relative error between them is less than 5%, so it can be considered that the fitting formula is feasible. (3) the lightning pressure U50 of contaminated insulator mist decreases with the increase of fogwater conductivity 纬 20. And the trend of saturation. In order to study the influence of foggy water conductivity on the lightning voltage of contaminated insulators, the additional salt density is defined. The fog flash voltage of polluted insulators can be expressed as U50A sa, and the formula is added salt density / mg / cm 2. The additional salt density is approximately linear to the conductivity of fog water and can be expressed as b20c. By comparing the calculated values with the experimental results, the relative error is less than 7%, so the mathematical model can be considered feasible. (4) the lightning pressure of insulator AC fog in fog decreases with the increase of fog temperature. The main reason is that the increase of temperature can increase the solubility of the solution, make more NaCl dissolve, and reduce the viscosity of the solution. The velocity of ion movement in solution is increased. (5) the arc blowing effect of air flow plays a leading role in the shape of discharge arc of insulator in natural fog. When the local arc is formed until the flashover process, the wind speed is 0 ~ 5 m. The influence of air flow on the discharge arc shape of insulator in natural fog is small, which can be ignored, and when the wind speed is 10 ~ 15m, the influence of air flow on the discharge arc shape of insulator in natural fog is greater, mainly as the decrease of arc diameter. The discharge arc becomes a multi-branched body.
【学位授予单位】：重庆大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TM216

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