BESS Inverters Step Up as Grid Stabilizers in a Post-Inertia Power System

As coal plants and gas turbines retire across Europe, they take something critical with them: the rotational mass that once kept power grids stable. Now battery energy storage systems are being asked to fill that gap — if their inverters can rise to the challenge.

The physics are straightforward. Spinning generators carry kinetic energy that naturally resists sudden frequency swings. When one trips offline, the momentum of remaining machines buys precious seconds for the grid to rebalance. With renewables displacing thermal generation, that buffer is shrinking, and frequency deviations are growing faster and deeper.

Daniel Gerber of ABB Renewable Power argues that BESS inverters are technically capable of taking over stabilization duties — but only if they operate in the right mode. Conventional grid-following inverters lock onto existing voltage and frequency; they carry no inherent inertial response, and software-based controls introduce unavoidable latency.

Grid-forming inverters work differently. By acting as a controlled voltage source rather than a passive follower, they set local frequency references and respond to disturbances without waiting for the grid to move first. Through a virtual synchronous machine architecture, these systems replicate the dynamic behavior of rotating generators, injecting synthetic inertia during frequency events.

Beyond normal operations, grid-forming technology unlocks black-start capability — the ability to re-energize a completely de-energized grid from scratch, without relying on any external reference. As large hydroelectric plants and gas turbines continue to exit the generation mix, Gerber contends that BESS systems are increasingly the answer to the question of who restores power after a major blackout, provided their inverters and control architecture can reliably support the full recovery sequence.

Source: PV Magazine