Adaptive Inverter Frequency Support in Low-Inertia Grids with Varying Synchronous Generation Units

The shift towards renewable energy sources has accelerated in recent years, mainly due to global efforts to mitigate climate change effects. However, the growing penetration of inverter-based resources (IBRs) and the decommissioning of synchronous generators (SGs) have introduced significant challenges to frequency stability during power imbalances. Unlike SGs, conventional IBRs lack inherent inertia and droop characteristics, making the system more vulnerable to rapid frequency deviations and limiting its frequency recovery capability. This work proposes an adaptive coordination scheme for enabling frequency support from grid-following inverters during disturbances. The control scheme emulates virtual inertia, frequency droop, and damping capabilities, with its parameters dynamically adjusted according to the system’s operating conditions, particularly the level of available rotating inertia and the droop support provided by committed SGs. The aim is to enhance frequency performance in scenarios with low rotating inertia and high renewable energy penetration. The methodology is validated through simulations, based on realistic scenarios from the Cyprus power system, demonstrating that the proposed scheme allows the inverter to mimic the behavior of SGs and improve frequency response across various operating conditions.