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. The Organization for Cross-regional Coordination of Transmission Operators (OCCTO) ensures network balance by designing national Master Plans. It is encouraging to see the draft 6th Plan for grid enhancement between Hokkaido, Tohoku and Tokyo area for further renewable deployment of 4GW. Smart meter deployment was completed in the Tokyo area in 2021 and will be finalized nationwide in 2025. A second generation will be deployed from 2025.


  • 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.