Fixed-Time Virtual Inertia-Damping Control for Frequency Stability in Interconnected Microgrid Systems

The growing integration of renewable energy sources (RESs) has led to a significant reduction in power system inertia, posing challenges for grid stability. Unlike traditional power systems, which rely on physical inertia, modern microgrids (MGs) require virtual inertia support from external energy sources such as energy storage systems (ESSs). Electric vehicles (EVs) can be utilized as existing energy resources to improve inertial response, thereby minimizing the need for additional ESS and associated costs. To meet the demand of inertia, this paper introduces a novel fixed-time integral sliding mode virtual inertia and damping (FxT-ISM-VID) control strategy, designed to enhance frequency stability in multiarea MG that typically lack synchronous generation. A key feature of the proposed controller is its ability to quickly resolve frequency deviations within a predefined time frame, regardless of the initial system conditions. This ensures accelerated and predictable stabilization times. Moreover, the ISM control provides robustness against model uncertainties, fluctuations in RESs generation, and system parametric variations. A thorough analysis using Lyapunov-based method is developed to validate the stability of the designed control strategy within a fixed time. Simulation and HIL results of a two-area interconnected MG with stochastic load-generation variations, nonlinear generation, and realistic communication delays validate the effectiveness of the proposed FxT-ISM-VID control approach. It outperforms existing strategies, achieving an 87.6% reduction in frequency deviation, 86.56% faster stabilization time, and significant improvements in tie-line power fluctuations during heavy load integration.