Coordinated source–grid–load–storage planning for power system flexibility: A case study in China

Endowed with abundant wind and solar resources, Xinjiang serves as China's largest renewable power export province, playing a pivotal role in the Chinese power system's net-zero transition. However, the large-scale integration of variable renewable electricity (VRE) is currently constrained by rigid transmission corridors and insufficient system flexibility, resulting in substantial curtailment. Existing studies largely overlook coordinated Source-Grid-Load-Storage (SGLS) optimization at the provincial level and fail to quantify its system-wide impacts on the national scale. To bridge this gap, this study explicitly integrates SGLS flexibility resources into a power system optimization model, jointly planning SGLS investments and evaluating their techno-economic impacts on both Xinjiang and the overall Chinese power system. The results show that, to accommodate massive VRE growth during 2025 and 2050, Xinjiang requires 16.89 GW of flexibility retrofits for existing thermal power plants, 16.40 GW of new thermal power capacity, 257.45 GW of inter-provincial transmission lines, 14.92 TWh of shifted load, 4.87 TWh of curtailable load, and 209.38 GW storage. This coordinated SGLS planning facilitates an additional 487 GW of local VRE while avoiding 1843 GW of redundant capacity nationwide, thereby reducing total national investment by $58.2 billion. It also lowers both the VRE curtailment rate and the LCOE (levelized cost of electricity) for local renewables, thereby reinforcing Xinjiang's role as a strategic hub for China's low-carbon power transition.