Bilevel Optimal Capacity Configuration of Energy Storage in a Park-Level Photovoltaic-Storage-Charging System Considering Grid-Export Constraints

Under the goals of carbon peaking and carbon neutrality and the development of zero-carbon parks, the continuous expansion of distributed photovoltaic (PV) installations has made grid-export constraints increasingly prominent. To investigate their influence on energy storage configuration and system operation, this paper incorporates the grid-export ratio constraint into the planning and scheduling process of a park-level PV-storage-charging system. A bilevel optimization model is established, in which the upper level minimizes the annual total cost (ATC), while the lower level minimizes the annual operating cost (AOC), considering time-of-use electricity prices, PV curtailment penalty, power shortage penalty, and battery degradation cost. The model is solved by a genetic algorithm (GA) and CPLEX. The results show that, for the studied industrial park, the 20% grid-export ratio is an important case-specific turning point under the given PV capacity, load level, electricity price, storage cost, and grid-connection conditions. Compared with the scheme without energy storage, the scheme with energy storage achieves lower PV curtailment and better economic performance. Sensitivity analyses further show that the PV curtailment penalty coefficient, energy storage investment cost, and PV installed capacity affect the optimal storage configuration and system economics. This study can provide a reference for energy storage planning and operation optimization of park-level PV-storage-charging systems under grid-export constraints.