强风环境下瓷绝缘子的积污特性模拟研究

发布时间：2018-07-26 16:29

【摘要】：绝缘子在电力系统输电线路中起着机械支撑与电气绝缘的作用,其绝缘性能关系着电力系统的安全运行。高压以及超/特高压直、交流输电线路的快速发展对电力系统外绝缘提出了更高的要求,瓷绝缘子由于其特殊的优点被广泛应用于这类输电线路。但强风沙尘天气、环境污染以及雾霾等造成的污闪事故时有发生,对电力系统造成了不可估量的损失。因此,研究瓷绝缘子的积污特性,掌握其在自然条件下的积污规律,以有效减少污闪事故发生,从而保证电力系统和电气设备的安全运行具有十分重要的现实意义。本课题采用数值模拟方法重点对瓷三伞绝缘子的积污特性进行了研究。基于力学理论,对污秽颗粒在绝缘子附近的受力特性及运动行为进行了分析,获得了基于力学平衡和力矩平衡的污秽颗粒动态沉积条件,包括其被风迁离条件;简述了瓷绝缘子在本校风洞条件下的积污试验;基于能量的污秽颗粒沉积判据,从正负荷电比例、表面能、粒径分布三方面对瓷绝缘子积污特性的递进影响进行了数值模拟研究,以期减小风洞条件下模拟结果与试验结果间的误差,获得优化模型并验证其合理性。籍此,采用表面能优化模型研究了强风环境下瓷三伞绝缘子的积污特性,分析了其在实际直、交流110kV高压输电线路中风速、颗粒粒径、电压类型等单因素及多因素耦合作用对其自然积污特性的影响。结果表明:由从正负荷电比例、表面能、粒径分布三方面对风洞条件下瓷绝缘子积污特性的递进影响研究获得了基于能量的沉积判据优化模型;与试验结果比较,其模拟结果平均相对误差分别在上一步基础上依次减小(6.6%、21.5%、6.4%),且其随所施加直流电压的变化趋势更为相似,验证了该优化模型的合理性。应用该优化模型于强风环境下瓷三伞绝缘子,在110kV直、交流电压分别作用时,积污量随粒径增大而增大;随风速增大,前者积污量逐渐减小且渐趋平缓,后者在不同粒径时呈现不同的变化规律,但两者间的积污量差异逐渐减小,并趋于一致;当风速与粒径(u,dp)取值在[(13m/s,15m/s),(20?m,30?m)]时,积污量沿伞裙呈“U”型分布,且直流电压的作用大于交流电压的作用;否则,“U”型分布逐渐消失。绝缘子表面积污量直交比随风速的增大而减小且渐趋平缓。小风速(9m/s)时,积污直交比随粒径增大而增大;风速为11m/s时,积污直交比随粒径增大先增大后趋于不变;较大风速时(13、15、17、19m/s),随着粒径增大,积污直交比先增大后减小。此外,还获得了绝缘子上下表面的积污特性。
[Abstract]:Insulators play a role of mechanical support and electrical insulation in power system transmission lines, and their insulation performance is related to the safe operation of power system. The rapid development of high-voltage and ultra-high voltage transmission lines and AC transmission lines put forward higher requirements for external insulation of power systems. Porcelain insulators are widely used in this kind of transmission lines because of their special advantages. However, the pollution flashover accidents caused by strong wind and dust weather, environmental pollution and haze have caused incalculable losses to the power system. Therefore, it is of great practical significance to study the fouling characteristics of porcelain insulators and master the fouling law under natural conditions in order to effectively reduce the occurrence of pollution flashover accidents and to ensure the safe operation of power system and electrical equipment. In this paper, the numerical simulation method is used to study the fouling characteristics of ceramic three-umbrella insulator. Based on the theory of mechanics, the mechanical characteristics and motion behavior of contaminated particles near insulators are analyzed, and the dynamic deposition conditions of contaminated particles based on mechanical balance and moment equilibrium are obtained, including the moving condition of polluted particles by wind. The fouling test of porcelain insulator under the condition of wind tunnel in our school is briefly described, and the criterion of fouling particle deposition based on energy, from the positive load electric ratio, surface energy, In order to reduce the error between the simulation results and the test results under wind tunnel conditions, the optimization model is obtained and its rationality is verified by numerical simulation on the progressive influence of ceramic insulator fouling characteristics from three aspects of particle size distribution in order to reduce the error between the simulation results and the experimental results under the wind tunnel condition. In this paper, the surface energy optimization model is used to study the fouling characteristics of ceramic three-parachute insulators under strong wind conditions, and the wind speed and particle size in the actual direct and AC 110kV high voltage transmission lines are analyzed. The effect of single factor and multi-factor coupling on the natural fouling characteristics of voltage type. The results show that the optimization model of deposition criterion based on energy is obtained from the progressive influence of positive load ratio, surface energy and particle size distribution on the fouling characteristics of porcelain insulators under wind tunnel conditions, and the results are compared with the experimental results. The average relative error of the simulation results is decreased in turn from the previous step (6.6%), and the trend of variation with the applied DC voltage is more similar, which verifies the rationality of the optimization model. The model is applied to ceramic three-parachute insulators under strong wind conditions. When the 110kV is direct and AC voltage is applied, the fouling amount increases with the increase of particle size, and decreases gradually with the increase of wind speed. The latter shows different variation law at different particle size, but the difference between them decreases gradually and tends to be the same. When the value of wind speed and particle size (U / dp) is [(13m / s ~ 15m / s), (20m ~ 30m)], the amount of fouling is distributed in "U" shape along the umbrella skirt. The effect of DC voltage is greater than that of AC voltage, otherwise, the "U" type distribution gradually disappears. The direct cross ratio of surface area of insulator decreases with the increase of wind speed and becomes more and more smooth. At low wind speed (9m/s), the deposition cross ratio increases with the increase of particle size, when the wind speed is 11m/s, it increases first and then tends to remain unchanged, while at larger wind speed (1315151719m / s), it increases first and then decreases with the increase of particle size. In addition, the fouling characteristics of the upper and lower surfaces of insulators are also obtained.
【学位授予单位】：华北电力大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TM216

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