| In the altiplano and mountain of our country,more than 68 percent of area is 1000-3000 meters above the sea level,where there is more than 75 percent of the whole country's total water and electricity resources. West-east Electricity Transmitting Project is great decision-making and mark project to implement the Western Development. All the transmission lines of West-east Electricity Transmitting Project are inevitable to crossing the high altitude and icing areas. For the reducing of the air pressure and the absolute humidity,the electricity strength of insulators will drop obviously. Therefore,it must be considered the effect on the insulators" flashover voltage caused by the change of altitude and ice when the insulation cooperation of transmission lines are being designed. If still using ceramic and glass insulators,the size of tower will be enlarged because of extra high voltage grade,which will result in the increase of investment. So when the transmission lines are being designed,the composite insulators may be a better choice. Compared to the traditional ceramic and glass insulators,the composite insulators have the characters of light mass,high intensity,high pollution-withstanding and convenient preserving. So the composite insulators are widely used in the power system of most countries. This article,which researches on composite insulators' AC flashover characteristic in high altitude and ice environment,has significant science values in theory and can also create enormous economy benefit in engineering.With regard to the special environment of high altitude and ice,this paper mainly studies the effect of altitude (air pressure),icing states (ice amount) and icing water conductivity on the AC flashover characteristic of composite insulators. Furthermore,it analyzes the hydrophobicity of composite insulators in these environments. The main tests and researches are as following:To study the AC flashover characteristic of composite insulator in different icing states by imitating tests in multifunctional artificial climate chamber,and analyze the effect of ice amount and icing water conductivity on flashover voltage,put forward a flashover mechanism by analyzing the icing flashover process.To study the AC flashover characteristic of composite insulator in different altitude and icing states together by imitating tests in multifunctional artificial climate chamber,and mainly analyze the effect of altitude (air pressure) and ice amount on flashover voltage,and investigate the flashover mechanism.To investigate the effect of high altitude and icing on the hydrophobicity of composite insulators.Based on a series of tests and investigations,this paper draws some conclusions as following by processing and analyzing the test data.The minimum icing flashover voltage of composite insulators decreases with the increase of ice amount,and the tendency of it accords with exponential function. However,the relation of the minimum icing flashover voltage with icing water conductivity accords with power function. The minimum icing flashover voltage ofcomposite insulators can be expressed as:where y is theconductivity of icing water and W is the ice amount. For 10 kV compositeinsulators,the characteristic index n of icing water conductivity's effect is about0.0765 and the characteristic index b of ice amount's effect is about 2.26.On basis of the analysis of the flashover processes in three kinds of icing states,itgives out the flashover mechanism of icing composite insulators and points out theminimum icing flashover voltage is related to the icing states.The emendation formula of flashover voltage in high altitude and icing area can besimplified aswhere H and Ware altitude and ice amount respectively.The hydrophobicity of composite insulators decreases and even disappears with the increase of icing time in high altitude,however,the effect of icing water conductivity to it is not notable. |
PDF Full Text Request