Microgrids (MGs) often integrate various energy sources to enhance system reliability, including intermittent methods such as solar panels and wind turbines. Consequently, this integration contributes to a more resilient power distribution system. Additionally, battery energy storage system (BESS) units are connected to MGs to offer grid-supporting services such as peak shaving, load compensation, power factor quality, and operation during source failures. In this context, an energy management system (EMS) is necessary to incorporate BESS in MGs. Consequently, state-of-charge (SoC) equalization is a common approach to address EMS requirements and balance the internal load among BESS units in MG operation. This paper presents a comprehensive review of EMS strategies for balancing SoC among BESS units, including centralized and decentralized control, multi-agent systems, and other concepts such as designing non-linear strategies, optimal algorithms, and categorizing agents into clusters. Moreover, the paper discusses alternatives to improve EMS and strategies regarding the topology of power converters, including redundancy-based topology, modular multilevel converter (MMC), cascaded-based converter, and hybrid-type systems. Additionally, the paper explores optimization processes aimed at reducing operational costs while considering SoC equalization. Finally, second-life BESS (2-BESS) units are explored as an emerging topic, focusing on their operation within specific power converters topologies to achieve SoC balance.

The dc–dc bidirectional step-up interleaved converter coupled by a central capacitor in a cascaded topology is used as a bidirectional electric vehicle charging station for charging and discharging the battery of an electric vehicle. In this article, a unified (coupled) model is proposed combining all switching intervals in a single model, allowing the accurate analysis and a better design for the controllers. In addition, this solution enables not only stage 1 to regulate the dc-link voltage on the terminals of stage 2 but also to use a classical proportional–integral controller or an adaptive state-of-charge-sharing function as a control structure. Finally, stability analysis, simulations, and experimental results are accomplished to evaluate the effectiveness of the proposed approach.

This article proposes a coordinated and decentralized control structure for a dc microgrid (MG) powered by fuel cells (FCs) and energy storage units (ESUs). With the employment of ESUs in the dc MG, the balancing among their states of charge (SoCs) increases their lifetimes and improves the dc MG reliability. Assuming the FC as the main source, fast transients of load on the dc link can damage its membrane. In this context, the FC and ESUs show a complementary behavior during the transitory, while the possibility to change the energy shared between the sources at a steady state promotes the energy management system. The SoCs of all ESUs connected to the MG are balanced using a fuzzy controller. Furthermore, a low-pass filter in association with a droop controller can mitigate the stress caused by the fast transients on the FC terminals. The main benefits of using the fuzzy controllers are related to the practical simplicity of implementation and the fact that a high-speed link of communication between the FC and the ESUs is not needed. Additionally, Lyapunov’s indirect method performs the stability analysis of the dc MG. Finally, a laboratory-scale prototype evaluates the effectiveness of the proposed approach.

This paper presents an adaptive power-sharing methodology for management of dc microgrids powered by fuel cell (FC) and storage system (SS). In this context, the use of an adaptive k-sharing function in the control scheme is proposed to compensate the fast transients on the ac side and manage the power sharing at steady-state regime between the FC and SS. The adaptive k-sharing is implemented with a low-pass filter transfer function for the FC and a complementary transfer function associated with the adaptive k-sharing gain for the SS. The proposed adaptive k-sharing function links the FC and the SS dynamics with the management of the dc microgrid, ensuring that the entire FC operation is performed in accordance with its operational limits. One of the main advantages of the proposed adaptive k-sharing is to reach high levels of stability and minimum disruptions on the FC terminals. To evaluate the feasibility of the proposed approach, we analyze the k-sharing behavior to determine the operational limits of the dc microgrid. Finally, to support the theoretical analysis, we carried out a set of experimental results.

The connection of low power renewable energy sources, such as fuel cells, to the distribution generation system requires power electronics structures with high voltage gain, high capability to power processing and consequently, high levels of current flowing through the dc/dc converter. In this context, this study analyses how the parasitic resistances of the passive components and the load power demand affect the dc/dc converter voltage gain. Taking into account the mathematical model, the boundaries of operation of the Interleaved Boost with Voltage Multiplier converter is determined through a set of equations and by means of a graphical analysis. The theoretical analysis, simulations and experimental results are used to validate the proposed approach presented in this study.

In this study, the authors propose a method to implement a low‐cost hardware‐in‐the‐loop (HIL) system for power converters and microgrids design, test and analysis. This approach uses a digital signal processor (DSP) Texas Instruments as the HIL core. All the differential equations of the power converters are solved in real‐time by the DSP and displayed in the digital‐to‐analogue outputs. Three different converters are modelled in this study: boost converter, single‐phase inverter connected to the grid and three‐phase inverter connected to the grid. Experimental results are obtained and compared to the HIL response. These results were made triggering the real converter and the HIL with the same open‐loop pulse width modulation signal, showing high fidelity between the digital models over the real systems. In a second moment, a microgrid is modelled in the proposed HIL and tested with a closed‐loop controller. The experiments show that the proposed hardware supports time steps as low as 1 μs or 1 MHz update rate, depending on the model. The proposed technique has the potential to reduce testing time and cost, once commercial HIL devices such as Typhoon, dSPACE and RTDS have a significant cost, not affordable or available to all the research community