By replacing conventional generation units with renewable energy sources (RESs), the power system gains an alternate source of future power demand and a better environmental platform. RESs, on the other hand, are unable to provide the required power demand due to poor inertia responses and low-frequency stability. As a result, multiple inertia augmentation control strategies were developed to increase frequency stability and maximize power usage in the grid-integrated renewable energy systems. Accordingly, this study thoroughly reviews existing virtual inertia control (VIC) strategies for improving inertia response and frequency stability. This study investigates 51 VIC approaches regarding required parameters, configurations, key contributions, sources, controllers, and simulation platforms. Furthermore, to emphasize the most promising ones, the VIC approaches are classified as intelligent, adaptive, derivative, coordinated control, and other VIC techniques. The classification approach is followed by the system configuration and the mode of operation of each control scheme. Integrating intelligent methods, such as fuzzy logic, genetic algorithm, non-convex optimization, and heuristic optimization, signify intelligent control methods. In contrast, adaptive control schemes emphasize the adaptation of control operations. These studies include both the standalone and grid-connected RESs frequency and power control approaches with necessary mathematical modelling and equations, which are rarely available in the recent existing works. The current state of research on improving frequency stability and inertia response in the grid-integrated RESs is discussed. The scenario is presented based on the inertia and frequency regulation of various topologies under different circumstances. Finally, this literature review reflects the present status of VIC technique research paths, and the categorization and analysis of these approaches demonstrate an extensive insight into the research field.

In this paper, a nonlinear decentralized double‐integral sliding mode controller (DI‐SMC) is designed along with an energy management system (EMS) for the DC microgrid (DCMG). This DCMG includes having a hybrid energy storage system (HESS) that incorporates a battery energy storage system (BESS) and supercapacitor energy storage system (SCESS) while the load demand is met through the power generated from solar photovoltaic (SPV) units. First, dynamical models of each subsystem of DCMGs such as the SPV system, BESS, and SCESS are developed to capture highly nonlinear behaviors of DCMGs under various operating conditions. The proposed nonlinear DI‐SMC is then designed for each power unit in DCMGs to ensure the desired voltage level at the common DC‐bus and appropriate power dispatch of different components to fulfill the load requirement of the DCMG. On the other hand, an energy management system (EMS) is designed to determine the set point for the controller with an aim of ensuring the power balance within DCMGs under various operating conditions where the overall stability is assessed using the Lyapunov theory. Simulation studies along with the processor‐in‐loop validation, including a comparative study with a proportional‐integral (PI) controller, verify the applicability and effectiveness of the EMS‐based DI‐SMC under different operating conditions of the DCMG.

In this work, a control strategy is developed for different components in DC microgrids where set points for all controllers are determined from an energy management system (EMS). The proposed EMS-based control scheme is developed for DC microgrids with solar photovoltaic (PV) systems as the primary generation units along with energy storage systems. In this work, the concept of dual energy storage systems (DESSs) is used, which includes a battery energy storage system (BESS) and supercapacitor (SC). The main feature of this DESS is to improve the dynamic performance of DC microgrids during severe transients appearing from changes in load demands as well as in the output power from solar PV units. Furthermore, the proposed EMS-based control scheme aims to enhance the lifetime of the BESS in DC microgrids with DESSs and voltage stability as compared to the same without SCs. The proposed EMS-based control strategy uses proportional-integral (PI) controllers to regulate the switching control actions for different converters within the DC microgrid based on the decision obtained from the EMS in order to achieve the desired control objectives. The performance of the proposed scheme was analyzed through simulation results in terms of improving the voltage stability, maintaining the power balance, and enhancing the lifetime of BESSs within a DC microgrid framework incorporated with the DESS. The simulations are carried out in the MATLAB/SIMULINK simulation platform and compared with a similar approach having only a single energy storage system, i.e., the BESS.

This paper proposes a new composite scheme to design a robust voltage controller for DC-DC buck converters in which the composite structure combines the recursive backstepping approach with an integral terminal sliding mode controller (ITSMC). In this work, the proposed ITSMC is designed to overcome the one-degree limitation of existing ITSMCs and difficulties for the finite time convergence in standard sliding mode controllers (SSMCs) as it incorporates a quick reaching law. Moreover, the singularity problem in existing SSMCs is tackled using a modified integral sliding surface. The backstepping strategy is used to ensure the voltage monitoring with a higher degree of accuracy. The robustness of the proposed composite approach is ensured by capturing the variations in parameters, input voltage, and mismatch in the model; as all these factors are included in the dynamical model of the DC-DC buck converter based on which the proposed composite controller is designed. The robustness and stability of the proposed composite controller are simultaneously analyzed using the concept of the Lyapunov stability theory. The theoretical and analytical findings for the proposed composite robust backstepping ITSMC (RBITSMC) are further verified through extensive simulation studies in the MATLAB/Simulink platform. Performance comparisons of the proposed RBITSMC are also presented against an existing adaptive nonsingular fast terminal sliding mode controller (ANFTSMC). Finally, experimental results from the application of the proposed control strategy on a laboratory prototype are presented to justify its application on the practical system.