Minimum Frequency Support Strength Evaluation and Allocation of Inverter-Dominated Power Systems

To effectively supervise and regulate the frequency support strength of power systems with high penetrated inverter-based resources (IBRs), this paper proposes a novel minimum frequency support strength (MFSS) evaluation and allocation approach. Firstly, equivalent low-order models for grid-following (GFL) and grid-forming (GFM) IBRs are constructed and embedded into the system frequency model with various power resources. Subsequently, methods for simultaneously assessing the minimum inertia strength and frequency regulation strength of the system and IBRs, are introduced considering the rate-of-change of frequency and frequency nadir limits. Finally, a frequency control parameters allocation strategy of IBRs is proposed, which allocates the virtual inertia and droop coefficients based on the frequency spatial correlation and energy reserve status of IBRs, effectively enhancing the frequency support strength under variable operating scenarios. The effectiveness and superiority of the proposed model and approach are validated on a modified IEEE 39-bus test system and a provincial power grid in China.