Integration of renewable energy sources (RES) is one of the key factors in the fight against climate change and they are becoming to take a larger share in electricity production. The systems with a high penetration of RES have small rotational inertia and are more vulnerable in terms of frequency stability. This paper proposes strategy for multistage fast frequency control (FFC) provided by converter-connected resources. They can quickly change the output active power and provide frequency support immediately after the disturbance during the period before that frequency reaches its nadir. The proposed control strategy uses only local measurements of the rate of change of frequency (RoCoF) and there is no need for complex telecommunications infrastructure. The multistage approach enables dispatched reserve to be proportional to the size of disturbance. RoCoF based FFC provides that more reserves would be dispatched in low-inertia areas that are more sensitive to disturbance and therefore enhance frequency stability. The proposed control strategy is validated on a test system of 3 coherent areas and the simulation results confirm that more reserve is dispatched in low-inertia areas that are more affected by disturbance.
Frequency Stability Assessment of Grid-forming VSG in Framework of MPME with Feedforward Decoupling Control Strategy
