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.

Micro-inverters usually are used to connect photovoltaic panels (PV) to the electricity grid. If the energy provided by the panel is not enough to satisfy the demands, the system becomes dependent exclusively of the grid. This constraint demands the use of a battery bank, therefore it is necessary to add a third port to the micro-inverter to connect this energy backup. In this paper, a two stage micro-inverter is proposed, the first stage is a DC/DC Triple Active Bridge (TAB) converter that integrates a back-up battery and works in soft switching; and the second stage is a Voltage Source Inverter (VSl) that operates in both grid-connected mode (GCM) and Stand Alone Mode (SAM). The grid-multimode operation controller developed detects the islanding fault and maintains the energy quality for a typical nonlinear load. Reliability and robustness of Uninterrupted Power Supplies (UPS) are increased by the proposed control.

The widespread integration of renewable energy sources (RESs) into the grid through inertia-less power converters is reducing the overall system inertia leading to large frequency variations. To mitigate this issue, grid-forming (GFM) control strategies in bidirectional battery chargers have emerged as a promising solution, since the inertial response of synchronous generators (SGs) can be emulated by power converters. However, unlike SGs, which can withstand currents above their rated values, the output current of a power converter is limited to its nominal design value. Therefore, the estimation of the power delivered by the GFM power converter during frequency events, called Virtual Inertia (VI) support, is essential to prevent exceeding the rated current. This article analyzes the VI response of GFM power converters, classifying the dynamic behavior as underdamped, critically damped, or overdamped according to the selected inertia constant and damping coefficient, parameters of the GFM control strategy. Subsequently, the transient power response under step-shaped and ramp-shaped frequency deviations is quantified. The proposed analysis is validated using a 1.2 KW single-phase power converter. The simulation and experimental results confirm that the overdamped response under a ramp-shaped frequency event shows higher fidelity to the theorical model.

A novel control strategy is proposed for a bidirectional multiport single phase two stage microinverter without electrolytic capacitor. The application of this converter is for power factor correction under non-linear grid tied load. The converter is composed of a triple active bridge series-resonant DC/DC converter cascaded with a voltage source inverter where a film capacitor is used in the DC-Link. Power decoupling is obtained due to a high ripple low frequency voltage in the DC-Link. The proposed controller has three cascaded loops to control the DC-Link average voltage, the instantaneous grid current and the point of common coupling voltage respectively. This strategy allows having a high speed steady-state response, good stability, low harmonic distortion in the grid, bidirectional power flow and low computational cost unlike other controllers. Two different cases have been tested, the first one when only the grid delivers power to the non-linear load, and the second one when the power flow is shared between the grid and any other DC source (renewable source or battery). Simulation results validate the controller functionality.

The increasing penetration of renewable energies into the power grid, predominantly interfaced through power electronic converters that lack inherent inertia, has led to significant challenges, including inertia reduction and transient voltage deviations. To address these concerns, the configuration of single-phase bidirectional electric vehicle chargers (BEVCs) into a three-phase arrangement, incorporating vehicle-to-grid (V2G) functionalities, has been identified as a promising solution. This paper presents a novel control strategy to enable the provision of V2G services—including virtual inertia (VI), long-term frequency-watt support, and voltage-var regulation—in a single-phase BEVC architecture powered by a hybrid energy storage system (HESS). The proposed BEVC topology consists of a dual active bridge (DAB) resonant-type DC-DC converter linked to a voltage source inverter (VSI). The HESS comprises DCL capacitors and a lithium-ion battery, enabling the decoupling of the BEVC's active power response from grid frequency disturbances. Specifically, the fast dynamic response required for VI emulation is handled by the DC-link capacitors, while the slower response associated with long-term frequency support is provided by the EV battery. As a result, the virtual inertia support is delivered without adversely affecting battery lifespan. Experimental validation using a 1.2 kW prototype demonstrates the effectiveness of the proposed control strategy.