Large-scale battery storage can destabilize strong power grids, study finds

A new IEEE-accepted study from Qiang Fu and colleagues challenges the long-held assumption that inverter-based resource (IBR) instability only arises under weak grid connections. Using large-scale energy storage systems (ESSs) as a practical case, the authors demonstrate that even strong grids can suffer from converter-driven oscillations when multiple power conversion systems (PCSs) interact. The ESSs in the study produced 150 Hz oscillations in the d-q reference frame while providing both capacitive and inductive reactive power support via their functional control loops.

As the scale of the ESS grows, these PCS interactions superimpose and intensify, progressively reducing oscillation damping and pushing the system toward instability. The paper highlights that ESS functional control loops—designed to support the grid—carry hidden instability risks under strong grid conditions. Using SIMULINK simulations, the researchers identify major impact factors (e.g., control loop tuning, number of units) that can mitigate the oscillations.

This work is a wake-up call for grid planners and energy storage operators: strong grid connections do not automatically guarantee stability. Careful planning of ESS scale and control design is essential to avoid unexpected 150 Hz oscillations that could disrupt power quality or trigger protection systems.