Study of overvoltages on /spl plusmn/800 kV UHVDC transmission system

This paper investigates the causes and characteristics of the overvoltage of /spl plusmn/800 kV UHVDC transmission system under operation and fault conditions, and the factors which influence the overvoltage level. A complete simulation model is built based on the design aspect of the upcoming Yun-Guang UHVDC Transmission System scheme by PSCAD/EMTDC. The overvoltages under various conditions are calculated. By comparing with /spl plusmn/500 kV HVDC transmission system, the particular characteristic of the overvoltage of UHVDC transmission system is summarized. Based on this, the basic rules for insulation margin and insulation level are given. The effect methods to prevent and limit overvoltage are discussed, and some beneficial results are obtained.