Regional adaptive hydropower-pumped storage collaborative planning for low-carbon transition: Flexibility enhancement and benefit evaluation based on resource endowment differences

Large-scale integration of wind and solar power combined with the progressive decommissioning of conventional coal-fired power plants poses significant challenges to power system flexibility. Although hydropower and pumped storage can provide flexible regulation, China's regional water resource endowments vary significantly, and their impacts on low-carbon transition across different regions have not been systematically quantified. Therefore, this study proposes a three-step collaborative modeling framework, developing a MESSAGEix power generation system planning model aimed at minimizing system costs and a DISPASET unit commitment optimization model that precisely captures hydropower unit operational characteristics, proposing differentiated hydropower flexibility retrofitting and pumped storage collaborative planning schemes. A multi-dimensional comprehensive evaluation index system encompassing economic, technical, environmental, and social dimensions was established, with planning schemes for various provinces scientifically evaluated through the CRITIC-TOPSIS multi-criteria decision-making method. Results show hydropower flexibility retrofitting reduces loss-of-load hours in Xinjiang and Shaanxi by 6 h and 20 h respectively, while variable-speed pumped storage achieves greater reductions of 40 h and 166 h, both improving renewable utilization by 0.6%–17.8%. By 2030, variable-speed schemes perform best for Xinjiang and Shaanxi, while Yunnan's basic scheme excels; by 2060, incremental pumped storage schemes for Xinjiang and Shaanxi, and variable-speed scheme for Yunnan demonstrate optimal performance.This research provides theoretical support and empirical evidence for differentiated hydropower and pumped storage planning