Transmission and distribution

Japan’s transmission network is centred on its production sites, with the main transmission at 500kV. The frequency convertor stations (FC) connecting the 50Hz and 60Hz networks offer only limited additional capacity. Furthermore, the limited interconnections between the individual EPCOs represent a real risk to security of supply. In contrast, European and US grids have extensive plans for use of High Voltage Direct Current (HVDC), which offers more flexibility in energy flows between regions, enables large integration of renewable into the system and also enables long cable connection by subsea or land. It is encouraging to see the draft 6th Plan for grid enhancement between Hokkaido, Tohoku and Tokyo area for further renewable deployment of 4GW.


  • The legal unbundling in April 2020 should implement regulations that will ensure security of supply and fair market mechanisms based on wider grid interconnections and look into increasing ownership or operation separation to further ensure the independence of Transmission and Distribution System Operators (TDSOs).
  • Japan should do more to increase interconnection capacity between TDSOs, achieving fair electricity transactions and encouraging mergers between TDSOs for logical and reasonable decision making.
  • The TDSOs should look into further harmonisation of technical standards by integrating individual requirements and also adopting European standards for products and systems to achieve cost efficiency.
  • Japan should consider interconnections with other countries using HVDC connections. In principle, this is same as LNG carriers which is another way of energy transportation for import and export.