Planning of renewable sources and energy storages and retirement of coal plants with unit commitment reserving operational flexibility

The key issue in the low-carbon transformation of the power system is to plan for the orderly retirement of the existing coal-fired power units when they reach the end of their service life. Here, we present a renewable and storage planning model considering the retirement of coal plants. Increased share of renewables will bring the conflict between the temporal variability and system flexibility into the system. Therefore, we embed the unit commitment into the long-term planning model to fully consider the system flexibility. The proposed model was verified in the HRP38 test system with a high percentage of renewable energy penetration rate. The planning results were analyzed from the perspectives of carbon policy and storage price. The results showed that reasonable planning for renewable energy expansion and energy storage investment can achieve carbon reduction.