Responding to various challenges for introducing renewable energy

Tokyo Electric Power Company Holdings, Inc.

Image of power supply in Hahajima Island

Outline

The "The Fifth Strategic Energy Plan" approved by the Cabinet on July 3, 2018, lists initiatives to make renewable energy a main source of power as one of its important policies towards 2030. On the other hand, if the introduction of decentralized energy sources centered on renewable energy advances and the output of centralized power sources, such as thermal and nuclear power, decreases relatively, it occurs a possibility that the electric power system will not be able to withstand instantaneous fluctuations in supply and demand in the future. Tokyo Electric Power Grid Co., Ltd. (Hereinafter referred to as our company) will continue to fulfill its responsibility as a neutral and fair power transmission and distribution network operator that provides stable electricity, and will address various issues associated with the interconnection of distributed power sources to systems.

Description

We are taking the following initiatives responding to various issues related to expanding the volume of renewable energy.

● Problem of insufficient transmission capacity
Due to an increase in power flow from renewable energy sources, some power transmission lines are running short of acceptance capability for them, and transmission line reinforcement work is required to resolve the capacity shortage. Our company is working toward the implementation of power transmission line reinforcement works through the application process for power connection projects.

● Voltage rise problem
If the reverse flow of electricity occurs in the power system due to the expansion of solar power generation, the voltage may rise and deviate the appropriate voltage range (95 V to 107 V). Our company is working to reduce voltage surges by increasing pole transformer and installing automatic voltage regulators (SVR).

● Frequency adjustment problem
Since electricity cannot be stored, it is necessary to keep the balance between electricity supply and demand consistently. Since the renewable energy supply varies greatly depending on weather conditions, it is necessary to adjust the frequency, which is one of the essential qualities of electric power. If more renewable energies are introduced, it is necessary to take measures such as controlling the output of renewable energy and utilizing storage batteries. Our company retains the frequency adjustment power such as thermal power and pumped-storage power and addresses verification tests to optimize the control between renewable energy and storage batteries.

● Supply-demand balance and surplus power problem
If a large amount of solar and wind power generation is introduced, it occurs a possibility that the base supply capacity added on the output of solar and wind power will exceed the demand at a time when the demand of electric power is low, resulting in a surplus of electric power, which may cause the instability of electricity supply and demand. In order to solve this problem, it is necessary to maintain the balance between supply and demand by absorbing excess power through pumped-storage power generation and by controlling the output of solar and wind power generation. Our company is promoting the development of renewable energy control systems and the improvement of accurate prediction through national projects and other schemes.

Partner(s)

Tokyo Electric Power Grid Co., Ltd.

Supplementary information

● Implementation of "Development of next-generation power network stabilization technology for the mass introduction of renewable energy" (June 25, 2019 Press Releases)
http://www.tepco.co.jp/pg/company/press-information/press/2019/1515546_8614.html

● Agreement on 100% renewable energy supply in Hahajima Island
(December 21, 2018 Press Releases)
http://www.tepco.co.jp/pg/company/press-information/press/2018/1511826_8687.html