Overall assessment of output control volume using detailed simulationsOutput Control Assessment Service for Non-Firm Connections

Assessment of output control has become the key

Non-firm connections, which allow new connections by electricity producers without limitation or guarantee, subject to output control during grid congestion, have become the standard from fiscal 2023 due to the increased introduction of renewable energy. For electricity producers to carry out business decisions and financing, comprehensive assessments that take into consideration output control for conventional factors for electric power supply and demand in addition to factors in electrical power systems are essential.

Visualization of roles and responsibilities of non-firm connections
＜Source＞ Organization for Cross-regional Coordination of Transmission Operators, Japan

Know-how regarding electrical power system simulations is necessary

A number of people with experience in the operation of electric power companies’ large-scale and complex electrical power systems are employed at TEPSCO. Based on their abundant knowledge and high level of technical ability cultivated through actual operation, we provide an output control assessment service in response to various scenario and examination needs by conducting electrical power system simulations in addition to electric power supply and demand simulations with multiple scenarios.

Renewable energy and grid storage batteries

Grid storage batteries are gaining attention as they balance supply and demand adjustments due to the increased introduction of renewable energy with output fluctuations and the decrease of thermal, etc. power sources that can be adjusted. Applications for connection examinations, etc. have been increasing, primarily in Hokkaido, Kyushu, Tokyo, and Tohoku. However, the issue for grid storage batteries is how the impact of output control should be examined as they are capable of charging and discharging at rated capacity for 24 hours a day, 365 days a year, which differs from renewableenergy such as solar power.

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  Visualization of output control for solar power generation
  ＜Source＞ Output Control: “I See! Grid” by Agency for Natural Resources and Energy

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  Visualization of output control for grid storage batteries

Visualize what customers want to know

As charge and discharge times are not set for grid storage batteries, it is difficult to assess what kind of impact output control has. TEPSCO will conduct electrical power system simulations and give instructions regarding the maximum amount of output control for the charging (and discharging) of grid storage batteries.

Example of calculation results for the percentage of grid storage batteries’ chargeability

(Unit: %)
(Note) Percentage of grid storage batteries’ chargeability = 100% - output control percentage

Output control assessment service and value provided to customers

• Conduct detailed (365 days a year, 24 hours a day) electric power supply and demand simulations over a business period (20 to 30 years) under a scenario decided by the customer
• ∗ Give instructions to customers about various choices regarding each item to be set for carrying out simulations(information on electric power demand, power source, and electrical power systems) from published information
• Carry out detailed mock simulations for electrical power systems in each area, and conduct comprehensive assessments of output control volume (also provide consultations for simple examinations limited to local systems)
• ∗ If output control is expected to occur primarily due to local electrical power system constraints