Comparatively analyzing synergistic benefits of hydro-wind-solar integrated power stations

Hydro-wind-solar integrated power stations have been a novel dispatching paradigm for power grids in southwestern provinces. However, due to the volatility of hydro-wind-solar power outputs, seasonal variations in hydropower regulation capacity, and the complex coupling between water regulation and power dispatching boundaries, the synergistic benefits of such integration are difficult to accurately assess, leaving the exploration of new dispatching mechanisms without a solid foundation. This paper first clarifies the connotation and differences between synergistic and non‑synergistic operation of hydro-wind-solar complementary operation. Considering multiple requirements such as renewable energy accommodation, transmission channel utilization, and source‑load matching, a benefit indicator system for integrated operation is constructed. Second, to meet the needs of long‑, medium‑, and short‑term dispatching, multi‑timescale optimization simulation models for both synergistic and non‑synergistic operation are established. The models employ mixed‑integer linear programming (MILP) techniques to handle complex non‑convex nonlinear constraints, achieving efficient solution. Finally, three differentiated hydro-wind-solar integrated stations (LHK, YZ, and JG) are taken as case studies. The operational benefits of synergistic versus non‑synergistic operation are compared in detail under long‑, medium‑, and short‑term horizons as well as wet and dry inflow scenarios. Based on the results, a preference atlas for dispatching modes of hydro-wind-solar integration is developed. It is found that when transmission channel capacity is sufficient, there is no significant difference between synergistic and non‑synergistic operation; when channel capacity is constrained, the synergistic benefits become obvious. By leveraging reservoir storage to shift hydropower electricity over time, it is possible to reserve channel capacity for renewable energy and reduce curtailment due to congestion. The results can provide a reference for the establishment of dispatching systems for watershed-scale hydro-wind-solar integration.