Adaptive Sliding Mode Control for Stability Enhancement of Grid-Forming Converters in Renewable-Dominated Microgrids

This study presents an adaptive sliding mode control (ASMC) strategy for improving the stability and performance of grid-forming (GFM) converters in renewable-dominated microgrids. With the growing integration of inverter-based renewable energy sources, maintaining system stability has become increasingly challenging due to reduced inertia and frequent disturbances. GFM converters, unlike grid-following counterparts, can independently regulate voltage and frequency, making them essential for future resilient power systems. However, their transient stability and response to faults require further enhancement. To address these problems, an ASMC framework is developed based on a reduced-order frequency dynamics model derived from the swing equation. The controller incorporates an adaptive gain mechanism that adjusts dynamically to system variations, ensuring robustness, fast convergence, and reduced chattering. The control structure integrates hierarchical power, voltage, and current loops, along with a current-limiting mechanism for protection under fault conditions. Simulation results validate the effectiveness of the proposed approach. The system achieves excellent frequency regulation with a maximum deviation of 0.00044379 Hz, zero overshoot, and near-instantaneous settling time. A low peak rate of change of frequency (0.012142 Hz/s) confirms smooth dynamics. Additionally, strong disturbance rejection, stable Lyapunov energy convergence, and accurate power tracking (MSE of 0.0021844 pu²) demonstrate the controller’s robustness and reliability in renewable-rich microgrids.