System Aspects of 1100kV AC Transmission Technologies in Japan: Solutions for Network Problems Specific to UHV AC Transmission System and Insulation Coordination

For development of a UHV transmission system, sophisticated system design is indispensable to deal with increased charging MVA and higher transmission voltage. Furthermore, for realization of technical and economical optimization throughout the design of the transmission line and the substation, solutions for network problems specific to UHV AC transmission system and problems with insulation coordination were sought in Japan. They include secondary arc extinction, fast multiphase reclosing systems employing HSGS (High Speed Grounding Switches) and overvoltage control by the use of surge arresters and circuit breakers with closing/opening resistors. These sophisticated technologies realize highly reliable and economical 1100kV substations and transmission lines. This paper describes the system aspects of 1100kV AC transmission technologies as well as experimental results of air insulation and secondary arc extinction.