Optimal Planning of Battery Storage to Enhance RES Integration and Frequency Security: A Planning-Validation-Adjustment Framework

The integration of a high proportion of renewable energy sources (RES) poses severe challenges to the flexibility and frequency stability of power systems. More battery storage systems (BES) are essential for supporting RES integration, with the fast frequency response (FFR) of grid-forming BES being particularly crucial for frequency stability. However, incorporating frequency dynamics into planning models is challenging due to the complexity and difficulty in model tractability. To address these issues, a two-level 'Planning-Validation-Adjustment' framework is proposed for grid-forming BES planning. The system frequency response model is integrated into the conventional planning model, and a frequency-dynamics feasibility-driven Benders-cut mechanism is developed to iteratively adjust BES planning decisions based on frequency response feedback. Specifically, the upper-level planning model optimizes the allocation and sizing of grid-forming BES under RES uncertainty scenarios. In the lower level, the FFR of grid-forming BES is incorporated into robust dynamic frequency constraints to ensure safety margins under uncertain power disturbances. When frequency violations are identified in the lower-level model, corresponding Benders-cuts are generated and fed back to the upper level to update planning decisions. To efficiently solve the proposed model, a Benders-Cut-based iterative solution algorithm embedded with progressive hedging algorithm (PHA) is developed. Simulation studies on the modified IEEE 39-bus system confirm the effectiveness of the proposed planning framework and solution approach.