The optimization of 750kV anti-ice-flashing composite insulator string

Composite insulators have been widely used for its excellent flashover endurance capability, but the umbrella of standard composite insulators are easily been bridged in icing condition. Flashover problems caused by icing insulator have a serious threat to the safe operation of transmission lines,. It is the key technologies for the safe operation of power system which should be solved as soon as possible. The influence of two types of composite insulator umbrella structure (common type and anti-ice type) on iced AC flashover voltage characteristics in the same structure length, as well as same artificial pollution and artificial icing test conditions, but also the method of artificial iced flashover test on composite insulator were introduced. Iced flashover test results showed that the ice bridge formation could be prevented or extended if the umbrella structure design of anti-ice-type composite insulators was more reasonable. For the 750kV composite insulator under the same conditions of artificial pollution test (SDD/NSDD=0.08/0.48mg/cm²) and artificial icing test (when icing water converted to 20 °C, the conductivity is 100μS/cm and the iced thickness from 15mm), it is shown that AC iced flashover voltage of Anti-ice type increased 12%~28% than common type. Upon the existent theoretical and experimental results and based on a great of laboratory investigations carried out in environment laboratory of China UHV AC test base, for the first time this paper studies systematically the insulators shed optimization which will contribute to the designation for Ultra-UHV anti-icing composite insulators.