Renewable Energy Sources (RESs) are growing rapidly and highly penetrated in Microgrids (MGs). As a result of replacement of the synchronous generators with a large amount of RESs, the overall system inertia might be dramatically reduced which negatively affected the MG dynamics and performance in face of uncertainties, leading to weakening of the MG stability, which considers being a serious challenge in such grids. Therefore, in order to cope with this challenge and benefit from a maximum capacity of the RESs, robust control strategy must be applied. Hence, in this paper, a new application of robust virtual inertia control-based Coefficient Diagram Method (CDM) controller is proposed in an islanded MG considering high-level RESs penetration for enhancement the system’s validity and robustness in face of disturbances and parametric uncertainties. The proposed controller’s proficiency has been checked and compared with H-infinite controller using MATLAB/Simulink which approved that the CDM controller achieved superior dynamic responses in terms of accurate reference frequency tracking and disturbance reduction over H-infinite in all test scenarios. Thus, the proposed controller alleviates the difficulties of H-infinite controller such as the experience and necessary abilities to design the form of the weighting functions for the system. Consequently, the frequency stability is improved and approved that the proposed CDM based virtual inertia controller can significantly support a low-inertia islanded microgrid against RESs and load fluctuations.

Microgrids have a low inertia constant due to the high penetration of renewable energy sources and the limited penetration of conventional generation with rotating mass. This makes microgrids more susceptible to frequency stability challenges. Virtual inertia control (VIC) is one of the most effective approaches to improving microgrid frequency stability. Therefore, this study proposes a new model to precisely mimic inertia power based on an energy storage system (ESS) that supports low-inertia power systems. The developed VIC model considers the effect of both the DC-DC converter and the DC-AC inverter on the power of the ESS used. This allows for more precise and accurate modeling of the VIC compared to conventional models. Moreover, this study proposes a fractional-order derivative control for the proposed VIC model to provide greater flexibility in dealing with different perturbations that occur in the system. Furthermore, the effectiveness of the proposed fractional-order VIC (FOVIC) is verified through an islanded microgrid that includes heterogeneous sources: a small thermal power plant, wind and solar power plants, and ESSs. The simulation results performed using MATLAB software indicate that the proposed VIC scheme provides fast stabilization times and slight deviations in system frequency compared to the conventional VIC schemes. The proposed VIC outperforms the conventional load frequency control by about 80% and the conventional VIC model by about 45% in tackling load/RESs fluctuations and system uncertainty. Additionally, the studied microgrid with the proposed FOVIC scheme is noticeably more stable and responds faster than that designed with integer-order derivative control. Thus, the proposed FOVIC scheme gives better performance for frequency stability of low-inertia power systems compared to conventional VIC schemes used in the literature.

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.