Enhancing Economic Sustainability in a Multi-Energy Hybrid System: Hydropower, Photovoltaics, and Energy Storage Integration

The integration of renewable energy sources, including hydropower and photovoltaics (PV), with energy storage systems (ESS) is pivotal for advancing sustainable energy transitions. This study investigates the economic and environmental optimization of a cascade hydropower-PV-storage hybrid system, aiming to enhance renewable energy utilization and mitigate environmental impacts. A mixed-integer linear programming (MILP) model was developed to optimize system operations, incorporating constraints such as hydropower generation, PV output variability, and ESS capacity. Nonlinear constraints, including water flow-reservoir capacity relationships and turbine vibration zones, were linearized to enhance computational efficiency. The model was solved using MATLAB with the CPLEX solver, and a case study in central China was conducted to validate the approach. The results demonstrate that the hybrid system with ESS significantly reduces operational costs by $5 \%$ compared to scenarios without ESS, avoiding 13.8 million dollars in curtailment penalties. The study underscores the critical role of ESS in improving renewable energy integration and economic efficiency. The cascade hydropower system’s flexibility, combined with PV and ESS, establishes a robust framework for multi-energy complementarity. These findings provide valuable insights for policymakers and system operators to promote renewable energy adoption and achieve carbon neutrality goals.