Research Of Equivalence Of Corona Loss Measurements Of The Conductors Based On Corona Cage And Test Line

Corona loss of transmission lines is directly related to the reliability and economy of design of UHV transmission line. The most important factor that affects corona charge is the surface gradient of conductor. The influence of climate on the corona discharge is very complex and usually needs to be studied through experiment. This paper use finite element method (FEM) to simulate the surface gradient of single conductor of corona cage and line-to-plate, and that of bundle conductor of corona cage, test line and 750kV transmission line. In the present, the two most commonly used corona loss test methods are corona cage and test line of short distance, and we can estimate the loss index of actual transmission line with the results by the two methods. In order to understand the effect of the geometry of corona cage on corona loss, this paper respectively calculated the correction factor of effective corona loss of the corona cage, line-to-plate and test line through introducing the concept of effective corona loss, and studied the equivalence of corona loss. The tests carried on the small corona cage in North China Electric Power University, the large corona cage in UHV AC test base, single-circuit test line and double-circuit test line. By the use of an optical fiber digital corona measurement system, the corona losses of smooth wire and stranded conductor that are both in the small corona cage and line-to-plate have been measured; the corona losses of bundle conductor in the large corona cage have been measured and those both in the single test line and in double test line have been monitoring.The results show that, for the smooth conductor, the stranded conductor and bundle conductor, correction coefficient K can achieve a good equivalence of corona losses. Therefore, as the equivalent test methods of UHV AC test line, corona cage is the effective research for the problem of corona loss of UHV AC transmission line. Based on the above analysis, the paper uses the corona losses of conductor measured in removable corona cage in enviroment and climate chamber to calculate the equivalent corona losses of 750kV transmission line, in order to comprehensively evaluate the corona losses of 750kV transmission line.