Grid-Forming Control with Assignable Voltage Regulation Guarantees and Safety-Critical Current Limiting

Researchers Bhathiya Rathnayake and Sijia Geng have published a paper on arXiv introducing a novel nonlinear grid-forming (GFM) controller designed to stabilize modern power grids with high renewable energy penetration. The core innovation is a controller architecture that provides mathematically provable guarantees for voltage regulation while incorporating a hard safety layer to prevent equipment-damaging over-currents. This addresses a critical challenge in power systems: maintaining stability as traditional, inertia-providing generators are replaced by inverter-based resources like solar and wind farms, which require sophisticated control to mimic grid-forming behavior.

The technical approach combines a droop-based inner-outer control loop with a deadzone-adapted disturbance suppression (DADS) framework, making it robust against unknown grid voltage disturbances without needing detailed network parameters. On top of this, a minimally invasive safety filter, formulated as a single-constraint quadratic program using control barrier functions (CBFs), enforces strict current limits. The system is proven to be globally well-posed, with voltage errors converging to an assignably small residual set at an assignable exponential rate. Numerical simulations show the proposed DADS-BS controller offers superior transient performance and faster recovery during fault-induced current-limiting events compared to conventional PI-based GFM controls, marking a significant step toward more resilient and certifiably safe power grids.