Design of a Capacity Tariff Incentive Mechanism for Coal Power to Promote Energy Transition

[Objective] To enhance the role of the capacity tariff mechanism in facilitating energy transition and address the issues of imprecise compensation and insufficient incentives for low-carbon and highly flexible coal-fired generating units under the current mechanism，this study develops a capacity tariff optimization model that incorporates energy transition objectives for coal-fired units. [Methods] The study first analyzes the cost pass-through path of coal-fired units and constructs a three-layer nested modeling framework consisting of a unit operation decision model，a power market clearing model，and a capacity tariff optimization model，thereby forming a dynamic feedback chain among the “unit-market-region-mechanism”."On this basis，an incentive model for coal-fired units targeting energy transition is proposed，in which the incentive targets and compensation levels are determined based on unit flexibility and carbon emission levels，using a sorting algorithm. Simulation analyses are conducted for typical days in new energy-rich and hydropower-rich regions，considering both regional and seasonal variations. [Conclusions] Simulation results show that the flexibility-based incentive strategy can effectively promote energy transition in scenarios with high ancillary service demand，but may inhibit transition in low-demand scenarios. In contrast，the carbon-based incentive strategy demonstrates stable and positive effects on energy transition across all regions and scenarios，indicating broad applicability. All proposed incentive strategies lead to only marginal increases in end-user electricity prices（within 0.038 yuan/kWh），demonstrating their economic viability. [Conclusions] The capacity tariff mechanism for coal-fired power units should be implemented with differentiated regional and seasonal strategies，taking into account variations in power source composition and load characteristics. It is recommended to initially adopt a carbon-based incentive scheme in the current stage and progressively introduce joint incentives based on both carbon emissions and flexibility as renewable energy penetration increases.