Study On Contamination Characteristics Of Typical Insulators Tested In Wind Tunnel

Pollution flashover is a serious threat to the safe operation of power system, and pollution accumulation at the surface of the insulator is a necessary condition of insulator flashover. Therefore, understanding the pollution accumulation characteristics of the insulator surface is the precondition of the study on its flashover characteristics. However, the insulator surface contamination deposition process under the natural condition is affected by many factors, such as wind, electrostatic field, insulator structure and so on, which lead to that pollution accumulation process of the insulator surface is very complex and difficult to study.In this paper, on the basis of the summary of the existing research results, the environmental wind tunnel is used to simulate the contamination performance of typical insulator under different influencing factors. The influence of different factors on insulator contamination performance has been analyzed; then the pollution deposition performance of 4 types of typical insulator has been compared. Wind tunnel is not only easy to control the environmental parameters, but also low cost, good repeatability, which is conducive to the systematic study of the process of insulator contamination. The main research contents and conclusions of this paper are as follows:(1) By using the wind tunnel test platform, the distribution characteristics of insulator surface contamination in wind tunnel are analyzed. Contamination distribution of the insulator string exists start-end effect, and measurement of NSDD should be taken on insulator in the middle of insulator string. Contamination distribution on the insulator surface is uneven, pollution degree of bottom surface is greater than that of top surface, and pollution of leeward side is more serious than that of windward side.(2) Take XP-160 as test sample. The contamination accumulation characteristics of insulator in different wind velocity, particle concentration, relative humidity and wind direction was studied. It is found that the increase of relative humidity and uniform wind field on the surface will enable the NSDD increase and extend its time of reaching lag growth state; but the increase of wind speed and particle concentration will enable the NSDD increase and shorten its time of reaching lag growth state.(3) By using XP-160 insulator as tested sample. The effects of wind speed, relative humidity, particle size, particle concentration, and wind direction on the contamination of insulator surface were studied. It is obtained that wind speed increases will lead to NSDD on its surface raises and the higher wind speed is, the more obvious non-uniform pollution distribution of windward and leeward side becomes; the larger the relative humidity, the higher the NSDD, and when it’s up to 90%, the growth is more obvious. The decrease of particle size and the rise of its concentration, the NSDD will increase. When diatomite as source of pollution, the NSDD on its surface is larger; uniform wind will enable the average NSDD increases, but NSDD of top surface is smaller.(4) Based on 4 types of typical insulators, contamination characteristics of the 4 types of typical insulators in different wind speed, relative humidity and wind direction were analysed. The distribution of contamination of different insulators is mainly affected by the direction of flow and its own structure. Under crosswind, the average NSDD of insulator surface, from big to small, followed by XP-160, large-small umbrella composite insulator, LXY-160 and XWP2-160. The influence of relative humidity on insulators is different and the increasing speed of composite insulator is the slowest, porcelain and glass insulator have little difference. Under uniform wind, for disc-type XP-160 and LXY-160 insulator, NSDD on bottom surface is more serious, and NSDD on top surface is relatively small. However, for XWP2-160 and large-small umbrella composite insulator, the case is opposite.