Frequency division: the Japanese electricity network

The problems of uniting two different frequencies (50 Hz and 60 Hz) into a coherent electrical system, which provides a base for one of the most powerful industrial nations in the world, have kept Japanese power engineers constantly updating their technology. The author describes the Japanese power system and the reasons for the two different frequencies. The 50/60 Hz split occurs almost in the geographical middle of Honshu, the eastern half using 50 Hz. The capacities of the 50 and 60 Hz systems are about 45 and 65 GW, respectively. Most of the power exchanges are from the 60 Hz to the 50 Hz network. The two systems were first connected in 1965 by the Sakuma frequency-converter station. The advances made since then in frequency conversion are briefly discussed. The author also discusses the connection of the various Japanese islands with HVDC and HVAC links. Nuclear and thermal generation are discussed as are environmental issues