Inertia Compensation Control Method for PV-ESS Plants Based on Critical Inertia

Abstract The integration of large-scale photovoltaic (PV) power generation into the grid has led to a continuous weakening of grid inertia and deterioration of system frequency characteristics. To enable frequency control for PV power plants and avoid control modifications for a large number of PV units, this paper proposes a virtual inertia compensation control strategy for photovoltaic-energy storage system (PV-ESS) plants. First, the critical grid inertia maintaining frequency safety is solved based on grid frequency constraint indexes, and the grid inertia compensation target is determined combined with the actual inertia. Then, by calculating the inertia reduction amount of each PV-ESS plant to the grid, the virtual inertia compensation targets of each PV-ESS plant are allocated according to the proportion of the reduction amount; the inertia control gain is dynamically set according to the inertia compensation target and the state of charge (SoC) to make the PV-ESS plant respond to the inertia compensation target and ensure grid frequency safety. Finally, the effectiveness of the proposed control strategy is verified through a case study system.