Kyushu T&D Launches Japan’s First 15-to-30-Minute Curtailment Control System

Kyushu Electric Power Transmission and Distribution (T&D) is strengthening measures to reduce renewable energy curtailment. Curtailment refers to a measure in which transmission system operators (TSOs) control power generation output to balance electricity demand and supply. Due to its sunnier weather conditions and greater land availability, solar capacity has expanded in the Kyushu area, reaching 12.61 GW as of the end of September 2025. Consequently, curtailment volumes have increased, totalling 1040 GWh in FY 2025 (preliminary figures), equivalent to an annual curtailment rate of 6.1%.

To overcome this situation, Kyushu Electric Power T&D began operating a new curtailment control system on June 1 for online power plants connected to the extra-high-voltage grid. While online control was previously based on forecasts made one to two hours in advance, the newly developed system allows curtailment decisions to be made 15 to 30 minutes before actual supply and demand, enabling output control closer to real-time supply and demand conditions. Kyushu Electric’s initiative is the first of its kind in Japan and is expected to reduce annual curtailment volumes by several percent.

The company will first verify the system’s effectiveness focusing on solar power. Since solar generation (also other renewable sources such as wind) is highly weather-dependent, the advantage of the new system is that it determines curtailment volumes by reflecting weather conditions and demand trends immediately before the moment in question.

🔍 Shulman Commentary:

Coping with increasing curtailment orders has been one of the key challenges for renewable power generators in recent years. Generators are increasingly interested in deploying BESS assets at their plants to improve business viability and mitigate the impact of sudden curtailment orders.