Grid-Forming Energy Storage Planning Methodology for Enhancing Frequency Security in VSC-HVDC Receiving Grids

To integrate increasingly growing renewable power, voltage source converter-based high voltage direct current (VSC- HVDC) transmission technology is widely adopted for its large capacity and flexible controllability. However, the integration of large-scale renewable power and VSC-HVDC receiving power reduces the capability of synchronous generators, lowering grid inertia and weakening frequency regulation. This paper proposes a novel planning method for grid-forming (GFM) converter-based energy storage systems (ESSs) in VSC-HVDC receiving-end grids to boost frequency security. This paper investigates the frequency support mechanism of GFM ESSs and develops frequency security constraints by analyzing three key frequency security indices following disturbances. A comprehensive ESS planning method for typical scenarios is then proposed, which includes an objective function comprising coal consumption costs, unit start-up and shut-down costs, ESS charge-discharge and configuration costs, and wind curtailment penalties. The planning constraints cover system and power equipment limitations, ESS operational constraints, and frequency security constraints. The effectiveness of the proposed method is validated through simulations on a modified IEEE 6-bus system.