Distributed generation contribution to primary frequency control through virtual inertia and damping by reference conditioning

Abstract

Penetration of converter-based distributed generation units (DGUs) rises quickly in the power systems. These generation units, which do not have any rotating masses, reduce the total system inertia, thus challenging both frequency control and system stability. In this work, to allow DGUs to contribute to primary frequency control, a sliding-mode reference conditioning loop (SMRC) is proposed. In this way, the DGUs aim to constrain both frequency deviation and rate of change of frequency within the boundaries established in the grid codes. The conditioning loop only acts if there is a risk of exceeding any of the established boundaries. Through variable structure system theory is shown that the conditioning loop behaves like a temporary contribution of virtual inertia and damping. Simulation results show that the conditioning loop allows DGUs to contribute to improving primary frequency control performance. Thus, exceeding the established boundaries is avoided with efficient use of energy.