Quantifiable Frequency Support from Grid-Forming Converters with DC-side Current Limits in Grids with Synchronous Generators

A decentralized supplementary control for quantifiable primary frequency support from renewable generation interfaced with class-A grid-forming converters (GFCs) under dc-side current limitation is proposed. GFCs regulated by droop, dispatchable virtual oscillator control (dVOC), and virtual synchronous machine (VSM) strategies belong to this class. The approach requires communication of frequency measurements of GFCs from adjacent buses. The proposed controller guarantees asymptotic stability of power grids with generic configurations that include multiple synchronous generators (SGs) and GFCs under dc power flow approximation and a mild assumption on center-of-inertia based frequency dynamics model. Simulations on a simplified model of a 4-bus system and a detailed phasor model of IEEE 16-machine system show the effectiveness of the proposed approach.