Study On The Accuracy Of The Prediction System Of Insulators Pollution

With the frequent occurrence of fog and haze,the pollutants deposited on the surface of transmission line insulators have also increased.In the wet conditions,the soluble substances in these impurities will gradually dissolve in the water,which will greatly reduce the insulation level of the insulator.In severe cases,pollution flashover accident,a strong discharge phenomenon will occur.The damage of pollution flashover to the power system is great,and the traditional measures to prevent pollution flashover include:installing anti-pollution insulators,regular cleaning of insulators,increasing creepage distances,brushing RTV coatings,etc.However,these methods are relatively passive and cannot fully adapt to the climatic conditions and the complexity of atmospheric pollution.Therefore,an insulator contamination prediction system capable of effectively and accurately predicting the accumulation of insulators under different atmospheric and natural environmental conditions needs to be established.This will provide an effective tool for forecasting and preventing pollution flashover in the power sector.At present,research on insulator contamination prediction system has achieved certain results.The existing insulator pollution prediction system plays a certain role in the prediction of accumulated pollution.However,the accuracy of the prediction is still not perfect.It does not take into account the influence of different wind speeds on the deposition of pollutants on the surface of insulators,and also ignores the differences between the deposition characteristics of fine particles and large particles.In view of the above problems,this paper designs and builds an artificial haze test platform and uses artificially simulated insulators to accumulate dirt in a haze environment.Experiments were carried out to measure the surface area of insulators with fine particles less than 10μm at different wind speeds.The effect of the wind speed and particle size obtained from the tests on the fouling was added to the existing insulator contamination prediction system.In order to improve the system forecast accuracy,the prediction is more accurate.The main research work of this article includes the following aspects:(1)Analysis of the Causes of Errors of Analog and Experimental Values found that in the process of solving the discrete particle phase,the existing soil accumulation prediction system assumes that once all particles contact with the surface of the insulator,it is considered that the particles are deposited on the surface of the insulator,and the simulated value is generally higher than the experimental value.This assumption does not take into account that the deposition law of particles at different wind speeds during the actual fouling process is also different,and also ignores the difference between the sedimentation characteristics of small size particles and large size particles.(2)To reduce the error and improve the accuracy of the system.In this paper,an artificial fog haze test platform was designed and the artificial contamination experiments were carried out.During the experiments,four working conditions were selected according to the actual wind speed under hazy weather,experiments were carried out to simulate the process of contamination on insulator surface area with fine particles less than 10μm.At the same time,In each set of working conditions,the change of concentration of particles with different particle sizes in the test chamber was recorded.(3)Analytical test results showed that the particle diameters of different particle sizes have different decreasing amplitudes,according to the particle concentration reduction,particles smaller than 10μm can be divided into three particle size ranges:less than 0.6μm,0.6-2.5μm,and 2.5-10μm,the difference in the concentrations of the three species varies greatly.Among them,the concentration of particles in the interval of 2.5-10μm decreased the most;the decrease of particle concentration in the interval of 0.6-2.5μm was the second;the decrease in particle concentration in the interval below 0.6μm is the smallest and the concentration value is almost constant after the airflow is stabilized.(4)The accumulation rule of particles with different particle diameters under different wind speed conditions was obtained through experiments.On the basis of defining the particle concentration reduction ratio,the concentration reduction ratio of each particle size particle under different wind speeds was calculated.It was found that the particle concentration reduction ratio at low wind speeds is approximately equal;the concentration reduction ratio of particles at high wind speeds is also approximately equal,and both follow different fouling patterns.The relationship between the ratio of particle concentration reduction and particle size at high wind speeds and low wind speeds was obtained by curve fitting.When the wind speed is low,the relationship between the concentration reduction ratio β_c and the particle diameter d is:(?).At high wind speeds,the relationship between the concentration reduction ratio β_c and particle size d is:(?).(5)The pollution mathematical model of fine particles in the insulator surface is set up by using computational fluid dynamics method and combining with the pollution law obtained by experiment.First three-dimensional modeling of the insulator is performed,and the Euler method is used to describe the continuous gas-phase field,the Lagrangian method is used to describe the discrete particle field,choose the gas-solid one-way coupling method to solve the model,and the salt-dense,gray-density analog values of the insulator surface are obtained by solving the discrete phase.Then the calculation method and calculation formula to improve the simulation value are put forward according to the pollution laws of the fine particles,and the mathematical model is closer to reality after improving calculation..(6)On the basis of establishment of the pollution mathematical model of fine particles in the insulator surface,a more perfect prediction system of insulator pollution is established by a large number of numerical calculation.And using the system to calculate the salt-dense and gray-density on the surface of the insulators in the four stages of two experiment sites.comparing the salt-dense and gray-density correction values with the simulation value and the experimental values,it is found that the correction value and the experimental value increase and decrease are more consistent than simulation value,and the relative error between the two is reduced from 32%to less than 15%.The accuracy of the prediction system of insulator pollution has been greatly improved.