Important technologies applied for UHV AC substations in Japan

Abstract

SUMMARYThe Tokyo Electric Power Company, Inc (TEPCO) plans 1100 kV power network system in Japan in order to meet the steady increasing demand for electricity. Four‐hundred kilometer 1100‐kV‐designed double‐circuit transmission lines have already been constructed and are now operated at 550 kV. 1100‐kV substation equipment has also been developed.To realize the best design technically and economically throughout the transmission line and the substation, important technical solutions for network problems peculiar to the ultra high voltage (UHV) system have been introduced. They include insulation coordination, overvoltage countermeasures, and fast multi‐phase reclosing systems with high speed earthing switches (HSESs). The overvoltage countermeasures are realized by high performance metal oxide surge arresters (MOSAs), gas circuit breakers (GCBs) with closing/opening resistor, and disconnectors (DSs) with resistor. These sophisticated technologies realize highly reliable and economical UHV substations and transmission lines.This paper describes important, fundamental, and specific requirements for UHV substations such as their compactness, economical view, and environmental harmony. There are many technical/economical aspects to be considered on UHV substation and based on those considerations: (a) compactness, (b) less impacts to the environment, (c) optimizing cost, could be fulfilled.This paper also describes the technologies addressed to UHV class components such as the introduction of new concept “on‐site assembly transformer,” VFTO reduction countermeasure and the necessity of full‐scale seismic qualification test. Copyright © 2011 John Wiley & Sons, Ltd.