An evaluation method for the aggregate adjustable capability of photovoltaic-storage-charging stations considering local security constraints

As renewable energy penetration continues to rise, enhancing power system flexibility has become a critical requirement. Photovoltaic–storage–charging stations (PSCSs) are key components for enhancing local regulation capability and promoting renewable integration. However, evaluating the adjustable capability of such hybrid stations while considering security constraints remains a major challenge. This paper first analyzes the adjustable capabilities of all the resources within such a station based on the power-energy boundary (PEB) model. Then, an optimal formulation is proposed to obtain the adjusted parameters of the aggregate feasible region (AFR) model, which embeds low-dimensional linear models within high-dimensional linear models to improve the accuracy. To solve this formulation, it is transformed using duality theory and an alternating optimization algorithm is designed to obtain the solution. Finally, a multi-station adjustable capability aggregation method considering security constraints is introduced. Simulation results verify that the proposed method effectively reduces infeasible regions and improves smoothness of aggregated boundaries, providing an accurate and practical tool for flexibility evaluation in PSCSs and offering guidance for aggregators and system planners.