1. Note:The power transmission and transformation business is handled by J-POWER Transmission Network Co., Ltd., a wholly owned subsidiary of J-POWER.

Power transmission and transformation business in Japan

J-POWER Transmission Network Co., Ltd. operates approximately 2,400 km of transmission lines and nine transmission substations/converter stations. We contribute to widespread operation and steady supply for Japan’s power grid, including trunk transmission lines connecting regions and frequency converter stations connecting eastern and western Japan (with different frequencies).

  1. In response to the legal separation of the power transmission business as stipulated in the Electricity Business Act, J-POWER spun off J-POWER Transmission Network Co., Ltd. on April 1, 2020, to ensure fairness and transparency in the transmission and conversion business.
    J-POWER has released announcements of rules regarding grid use, work that can be done on consignment, and wheeling revenue and expenditures. J-POWER maintains the reliability of transmission and conversion facilities from a neutral position and promotes efficient capital investment and operation.

Contribution to power network enhancement

The optimal locations for renewable energy are far away from the power consumption areas (large cities). In order to expand the introduction of renewable energy, it is necessary to reinforce the power network to transport the electricity generated to the consumption areas. J-POWER Transmission owns and operates transmission and transformation facilities that utilize a wide range of technologies, including ordinary AC transmission lines, DC transmission lines, submarine cables, cables installed on bridges, and frequency conversion stations that enable the exchange of electricity between the regions with different frequencies, and possesses technologies and knowledge necessary for expansion of the power network.
J-POWER is carrying out preliminary work to upgrade the capacity from 300 MW to 600 MW of the Sakuma Frequency Converter Station, which connects the different frequencies of eastern Japan (50 Hz) and western Japan (60 Hz). The work is scheduled for completion in fiscal 2027 in accordance with the plan formulated by the Organization for Cross-regional Coordination of Transmission Operators (OCCTO).

Conceptual Diagram of Transmission/Transformation Business

Conceptual Diagram of Transmission/Transformation Business

Expansion of core transmission lines and inter-regional connection lines

Expansion of backbone transmission lines to transmit large amounts of electricity and inter-regional connection lines to transmit electricity across regions

Expansion of DC transmission facilities

Installation of DC transmission lines (submarine cables) to transmit electricity generated by renewable energy to power consumption areas

J-POWER Transmission owns DC interconnection facilities (submarine cable) for Hokkaido-Honshu HVDC Interconnection Line and Honshu-Shikoku Interconnection Line.
J-POWER Transmission succeeded in constructing Japan's first ultra-high voltage DC power transmission facility and developing a DC XLPE cable.

Expansion of frequency conversion stations

Expansion of frequency conversion stations to exchange electricity between eastern Japan (50Hz) and western Japan (60Hz).

J-POWER Transmission owns Sakuma Frequency Converter Station. New Sakuma Frequency Converter Station and replacement and expansion of related transmission lines are under construction.

Handling transmission business from a neutral position

(Japanese site only)

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