The massive integration of renewable energies into the grid using fast-response converters without inertia generates issues such as inertia reduction, temporary voltage violations, and power quality reduction. The system inertia reduction is a critical problem that could lead to grid frequency exceeding the acceptable range, resulting in undesirable load-shedding or even large-scale blackouts. To overcome these issues, the use of electric vehicle bidirectional chargers (EVBCs) implementing functionalities such as distributed virtual inertia (VI), long-term frequency support, voltage support by reactive power, and harmonics compensation, has been proposed as a possible solution. This article proposes a novel control strategy to manage a hybrid energy storage system (HESS) composed of dc-link capacitors and battery, through an isolated two-stage ac–dc converter (composed of a dual active bridge resonant type dc–dc converter cascaded to a voltage source inverter), intended for off-board EVBCs. The HESS management allows decoupling of the active power dynamic response since dc-link capacitors supply the fast dynamic response for VI support whereas the battery supplies the slower dynamic response for long-term frequency support, respectively. Hence, the VI support does not affect the battery lifetime. Simulations and experimental results are presented for a 2.5 kW prototype to validate VI, frequency-voltage support along with harmonics compensation.

This paper examines high-frequency disturbances in interconnected converters within dc microgrids, focusing on the effects of electromagnetic interference (EMI) filters and long interconnection cables. Understanding these phenomena is essential for systems with multiple power converters as it facilitates the identification and mitigation of voltage and current oscillations. The study investigates the beating effect in dc microgrids, providing an analytical derivation of the oscillation amplitudes at the beat frequency. It also explores how interactions between long cables inductive impedance and EMI filter capacitors can influence the system performance, distinguishing it from previous works. The study examines a dc microgrid consisting of two connected cascaded buck converters. Two scenarios are analyzed: one considers no filters between the two converters, while the other includes a low-pass filter (LPF), an EMI filter, and a cable feeder between them. The proposed theoretical models are validated using a 2 kW experimental prototype comprising two interconnected buck converters. In addition, the paper presents various strategies to mitigate the beating effect in dc microgrids, discussing their effectiveness and the associated implementation challenges.

This paper introduces a methodology to model and control a single-phase inverter with LCL filter intended for low power PV distributed generation in microgrid scenario. The system should operate in grid connected and island modes with a smooth transition between them. The control strategy is to split the system into two: the internal voltage subsystem and the external injected current subsystem. These two subsystems are modeled in state-space considering disturbances and uncertain parameters. By using linear matrix inequalities (LMI) two state-feedback H _∞ controllers are designed. The complete simulation results demonstrate the feasibility of the proposed control system.

This paper presents the analysis of some usual MPPT (Maximum Power Point Tracking) strategies intended for small wind energy conversion (up to 1kW) based on permanent magnet synchronous generators (PMSG), considering the stand-alone application for a novel buck-boost integrated inverter. Each MPPT method is analytically introduced and then it is simulated using MatLab/Simulink ^® considering standard conditions of wind and also commercially available turbines and generators. The extracted power in each case is compared with the maximum available power, so the tracking factor is calculated for each method. Thus, the focus is on the application to improve the efficiency of stand-alone wind energy conversion systems (WECS) with battery chargers and AC load supplied by inverter. Therefore, for this purpose a novel single phase buck-boost integrated inverter is introduced. Finally, the main experimental results for the introduced inverter are presented.