Pollution Flashover Performance Under Switching Impulse Of 110kV Insulator String

Pollution flashover of insulator,which will also occur under switching impulse, poses a grave threat to the operation security of electric network, and its voltage will decline as the altitude goes up or the air pressure decreases. The study of insulator's switching impulse performance offers an important reference value for external insulation design. Against a background of transmitting the electricity from the western areas to East China, designing and constructing UHV or EHV overhead transmission lines will undoubtedly get across those high altitude areas in western China where the climate is complex. Consulting abundant data at home and abroad, and making good use of the large-scale multi-functional artificial climate chamber of the state key laboratory of power transmission equipment & system security and new technology in Chongqing university, this essay carries a series of experimentations of pollution flashover performance under steep-front switching impulse of insulator under low air pressure. The main parts and results of this dissertation are as follows:First,an experiment of positive and negative switching impulse pollution flashover, which is to study the connection between SDD and the U50% of insulator string, has been done under normal air pressure on an artificial contaminated XP-160 insulator string of 7 units, an artificial contaminated LXY4-160 insulator string of 7 units and an artificial contaminated FXBW3-110/100 composite insulator string. The results show that the effect of SDD on the U50% of artificial contaminated insulator string follows a power function law, and that the positive discharge voltage is lower than the negative discharge voltage.Second,by simulating low pressure at different altitudes in an artificial climate room, this paper has conducted an experimental study on the positive and negative switching impulse pollution flashover of an artificial contaminated XP-160 insulator string of 7 units, aiming at studying the connection between U50% and three factors, i.e. SDD, temperature and air pressure. The test results indicate that: the U50% is reduced in power function as the SDD increases or the P/P0 declines. Temperature shows a strong effect on U50%, which decreases as the temperature increases. The connection between U50% and k=1-0.023(t-20) follows a power function law.Finaly,by revising the test results obtained under low air pressure from the effect of three factors, i.e. pollution, temperature and air pressure, the writer gets the expression of the U50% of an artificial contaminated XP-160 insulator string of 7 units under low air pressure.