Adaptive virtual inertial control for frequency stability in islanded microgrids using Walrus Optimization Algorithm and Sliding Mode Controller

Reliable frequency stability in islanded microgrids has become increasingly challenging due to reduced system inertia, high renewable penetration, and parameter uncertainties. This paper proposes an Adaptive Virtual Inertia Control strategy based on a Walrus Optimization–tuned Sliding Mode Controller (Walrus-SMC) to address these challenges. The proposed method dynamically adjusts virtual inertia while leveraging a robust sliding control law optimized to minimize frequency deviation and control effort. Three operational scenarios—medium inertia, low inertia, and parameter uncertainty—are investigated, alongside six disturbance conditions, including load variations, renewable power fluctuations, and islanding events. Performance is evaluated against conventional PID, IMC-PID, and H∞ -based Virtual Inertia Control using key metrics such as Integral Absolute Error (IAE), overshoot, settling time, and control energy. Simulation results demonstrate that Walrus-SMC achieves up to a 99.8% reduction in IAE compared to conventional methods across all scenarios, with negligible overshoot and smooth inertia adaptation. Under severe disturbances, a hybrid Walrus–Sliding configuration further enhances resilience, reducing IAE by more than 70% relative to standalone strategies. These findings establish Walrus-SMC as a high-precision, energy-efficient control framework for next-generation islanded microgrids. The proposed approach offers practical benefits for systems with high renewable penetration and lays the groundwork for real-time adaptive implementation and multi-node deployment. • Adaptive virtual inertia is embedded directly within sliding-mode dynamics. • Walrus Optimization jointly tunes inertia and SMC gains offline. • Near-invariant frequency response is achieved under low-inertia conditions. • Up to 99.8% IAE reduction is obtained compared to conventional controllers. • Robust performance is maintained under load, RES, and islanding disturbances.