The Survey of Insulation Problems of UHV Transmission System

The energy distribution and load center in China are very unbalanced, and along with the continued increase of power demand, the tendency of developing and building UHV power transmission line in China is inevitable. With the increase of voltage classification, insulation problem has become more and more important,. In this paper, some characteristics of overvoltage of UHV transmission system are presented. And some insulation levels of transformation equipments (including transformer, breaker, GIS) are discussed. Insulation level of UHV transmission line of China could be confirmed by analyzing the distance between transmission line and ground, the amount of insulator, support insulator and casing wear. According to China's national situation and operational experience of foreign countries, some advice is given. At last, it is pointed out that metal-oxide arrester (MOA) is the appropriate arrester to UHV power system, and ZnO valve element is the key part of MOA, which should be paid more attention to.