This paper investigates the impact of DC fault-limiting reactors (DCRs) on the dynamics of Modular Multilevel converter-based multi-terminal DC (MTDC) grids, with a particular focus on their damping and coupling characteristics. The first part examines the instability introduced by large DCR values using a simplified low-frequency model and a comprehensive small-signal analysis of a four-terminal meshed DC grid. A dedicated controller is proposed to stabilize the system and is compared with other mitigation measures, such as modifying the control mode and changing the power flow direction. The second part investigates the coupling effects of DCRs in DC grids, showing that the commonly assumed equivalent DC grid capacitance becomes invalid in the presence of DCRs. This leads to different conclusions regarding DC voltage support between stations, particularly during fast transient responses. All findings are validated through time-domain simulations of a four-terminal DC grid.

As the global energy landscape shifts toward sustainability, microgrids incorporating Photovoltaic (PV) generation and Battery Energy Storage Systems (BESS) are becoming essential in commercial and industrial facilities. This research tackles the challenge of maintaining uninterrupted power supply to sensitive loads when grid disturbances occur. We propose a novel loss-of-mains detection method capable of identifying grid faults in under 3 milliseconds—well within the 10-millisecond threshold required for critical equipment to ride through the transition without disruption. Building on this fast detection, we develop inverter control strategies that enable a smooth transfer from grid-following to grid-forming operation while limiting transient overvoltage and overcurrent. Additionally, a coordinated operating sequence is introduced to ensure grid code compliance and proper management of distributed energy resources throughout the islanding process. The complete approach is validated experimentally using a dedicated prototype and a Power-Hardware-in-the-Loop (P-HIL) microgrid demonstrator, confirming its effectiveness and advancing the technology readiness level toward real-world deployment.

This paper proposes a single-stage, isolated DC/AC inverter for uninterruptible power supplies that embeds an active input-power buffer within a multiport active-bridge architecture. The controller reshapes lowfrequency power pulsations by directing them to a dedicated buffer, so the energy source experiences near-constant power while the output remains sinusoidal and well regulated. For battery sources, this operating regime reduces low-frequency current cycling and depth-of-discharge ripple, easing electrochemical and thermal stress and thereby supporting longer service life. An averaged power-flow model based on the generalized harmonic approximation provides a direct mapping from port-power references to phase-shift commands, and a hierarchical scheme separates fast tracking from slow energy regulation. Design guidelines are presented for transformer interfacing, leakage modeling, phase limits, filter selection, and start-up management. The approach enables compact, single-conversion UPS designs with improved source decoupling and output quality and is readily extensible to bidirectional operation and renewable integration.

The growing integration of renewable energy sources and the privatization of energy systems are driving the restructuring of Power Distribution Networks (PDNs). Future PDNs are expected to evolve into distributed structures supported by Multi-Agent Systems (MASs). However, the autonomous actions of local agents create challenges for coordination, grid integration, and operational reliability, highlighting the need for advanced energy management solutions. This paper proposes a Peer-to-Peer-to-Grid (P2P2G) trading framework for efficient energy management in PDNs with autonomous agents. In the proposed framework, agents reduce operational costs by participating in P2P and P2G trading while respecting network operational issues. To address network constraints, Transactive Control (TC) signals and Network Charges (NCs) are introduced based on each agent’s contribution, enabling fair allocation of costs associated with congestion power losses through a transaction-tracing method. Furthermore, to preserve agents’ privacy and ensure scalability, a decentralized market-clearing process is developed using the Alternating Direction Method of Multipliers (ADMM). The effectiveness of the proposed approach is demonstrated through numerical studies conducted on modified IEEE 15-bus and 37-bus systems featuring various types of agents. Finally, results confirm that the framework not only respects agents’ preferences but also enhances PDN operation by alleviating congestion, reducing losses, and improving overall system efficiency.

In this article, the interoperability between droop-controlled Modular Multilevel Converters (MMC) with Grid-Forming (GFM) functionality in a 3-terminal DC grid is investigated. Two possible implementations of GFM control, namely Virtual Synchronous Machine (VSM-GFM) and matching-GFM, are combined with two implementations of DC voltage droop. A small-signal analysis on a three-terminal asymmetrical monopolar DC grid is conducted to identify the limitations of the control parameters related to system stability and dynamic performance. Time-domain simulations are conducted to analyze the effect of control parameters on system response. The results demonstrate the interoperability between the two control options, subject to some control parameter limitations.

This paper introduces a comprehensive framework for evaluating the reliability of modular MVAC-LVDC Solid-State Transformers (SSTs) based on their mission profiles. The proposed approach emphasizes the importance of accurately assessing the reliability of Medium-Frequency Transformers (MFT), which play a critical role in SST performance. The study presents: 1) a mission-profile-based methodology for analyzing MFT reliability; 2) a detailed process for estimating SST lifetime that accounts for both random and wear-out failure mechanisms; and 3) an exploration of how MFT reliability influences overall SST lifespan. Additionally, the paper outlines the design methodology for MVAC-LVDC SSTs and details the component selection process used in the reliability assessment. Two case studies—one involving an electric vehicle load and the other a data center load—are applied to a 6.32 MVA, 11 kV AC / 1 kV DC SST design. Results indicate that incorporating MFT reliability into the analysis may reduce the estimated SST lifespan by over 15%, highlighting the value of integrated reliability assessments in SST design. This assessment identifies components prone to failure, allowing for redesigns that improve resilience against mission-profile stresses and extend the overall converter lifetime.

This paper proposes a theoretical framework for assessing the reliability of medium-frequency transformers, combining random failure modeling with wear-out analysis of dielectric insulation. The method decomposes the transformer into discrete dielectric regions and estimates their lifetime based on thermal and electrical stress profiles derived from a specified mission-profile. A case study on a 170 kW, 15 kHz dual active bridge converter demonstrates the approach, using cycle counting, electrothermal modeling, and Monte Carlo simulations to predict regional insulation degradation. Results show that for the studied mission-profile, the medium-frequency transformer achieves a wear-out lifetime well beyond 25 years, with minimal electric stress observed under normal operating conditions. The framework helps identify critical insulation zones and supports more informed design and lifetime risk evaluation in high-frequency power electronic systems.

Currently, Modular Multilevel Converters (MMCs) have emerged as a state-of-the-art solution for electrical energy conversion, particularly in High Voltage Direct Current systems. In order to ensure efficient and stable operation, it is essential to implement appropriate control techniques. Conventional control strategies, such as Voltage Oriented Control (VOC) or predictive control, generally require direct measurement of grid voltages. However, in the presence of disturbances, such measurements can compromise the robustness and stability of the system. In order to address this issue, the present paper investigates a sensorless control approach based on Virtual Flux (VF) estimation, which eliminates the need for direct voltage measurement. The proposed control strategy is based on VOC, combined with a submodule balancing algorithm to ensure reliable MMC operation. This study evaluates two VF estimation techniques: one using a Low-Pass Filter (LPF) and the other employing a Second-Order Generalized Integrator (SOGI). The simulation results carried out in MATLAB/Simulink demonstrate that the SOGI-based approach ensures optimal dynamic performance, enhanced accuracy, and zero steady-state error. Furthermore, studies conducted under highly distorted voltage conditions highlight the superior robustness of this method compared to the LPF approach. These findings highlight the relevance of the proposed sensorless control strategy for MMC, particularly in wind energy systems where grid disturbances are frequent and reliable operation is critical.

This paper presents a real-time simulation framework for a dual active bridge converter, aimed at estimating component lifetimes under mission-specific conditions. The model analyzes component-level losses to evaluate both random and wear-out failures, including those of the medium-frequency transformer, which is often neglected in reliability studies. An online Monte Carlo analysis with real-time Weibull parameter fitting estimates the converter's failure probability density function, achieving over 95% accuracy between the fitted distribution and the Monte Carlo generated data. The real-time system model and health monitoring algorithm were run continuously for a week under an EV charging profile, demonstrating the method's ability to identify failure-prone components over time, supporting predictive maintenance and improved reliability planning.

This article presents a cost-based robust charging scheme for plug-in electric vehicle (PEV) integrated with the beneficial collaboration of photovoltaic (PV) system. The uncertainty of load/PV power and electricity price is incorporated into the proposed model. To handle the altering feature of the uncertainty resources and achieve a robust charging strategy, the information gap decision theory (IGDT) is utilized. Since the formulated IGDT-based charging model is inherently a multiobjective optimization problem, the nondominated sorting genetic algorithm type 2 (NSGA-II) is used to create the Pareto optimal solutions. To attain the best compromise solution, a fuzzy-oriented selection method is introduced. Moreover, to elucidate more effective constraints for the robust territories (RTs) associated with the uncertainty resources of the proposed model, an evaluation based on the deterministic and nondeterministic operation costs is discussed. To validate the proposed robust charging strategy, a power hardware-in-the-loop experimental setup is developed using OPAL-RT 5700. Furthermore, the effectiveness of the NSGA-II in terms of both robustness and convergence efficiency is validated through comparison with single-objective particle swarm optimization, multiobjective particle swarm optimization and GUROBI solver.

This article presents an improved position sensor fault-tolerant control (IPS-FTC) of the stator current components of the permanent magnet synchronous generator (PMSG). It ensures the generator's operation in post-fault conditions, which are required for uninterruptible power injection by renewable energy conversion systems (RECSs). The proposed method is based on sliding mode (SM) theory and overcomes the drawbacks of traditional position sensor fault-tolerant control (PFTC) methods. The developed approach is relatively simple, direct, and robust versus non-modelled quantities. Furthermore, it does not require stator voltage sensors, compared to other developed SM control techniques. The stability and convergence of the proposed approach are proven by simulation and experimental results.

The emergence of Multi-Terminal DC (MTDC) grids for offshore wind integration introduces challenges in modeling dynamic interactions and ensuring HVDC system stability. Accurate AC and DC grid equivalents are essential for converter compliance testing and control design, especially in a multi-vendor context, where interoperability issues may arise. This paper proposes two DC grid equivalent models: a simple RLC-based model for low-frequency dynamics, and a reduced-order frequency-dependent model (from order 47 to 5) to capture both low and high frequency behavior based on DC-grid impedance fitting. The two models can effectively capture different DC grid variations, such as variations in DC Reactor (DCR) size, control modes, and operating points. Their applicability is demonstrated through frequency-domain impedance analysis and time-domain simulations of a 3-terminal DC grid with detailed MMC models. A case study is presented to highlight the importance of representing higher frequency dynamics for stability analysis. In addition, the frequency-dependent model is implemented in time-domain simulations to bridge the gap between stability analysis in the frequency and time domains.

Wind power systems, which are currently being constructed for the electricity worldwide market, are mostly based on Doubly Fed Induction Generators (DFIGs). To control such systems, multilevel converters are increasingly preferred due to the well-known benefits they provide. This paper deals with the control of a standalone DFIG-based Wind Energy Conversion System (WECS) by using a three-level Neutral-Point-Clamped (NPC) converter. The frequency and magnitude of the stator output voltage of the DFIG are controlled and fixed at nominal values despite the variable rotor speed, ensuring a continuous AC supply for three-phase loads. This task is achieved by controlling the DFIG rotor currents via a PI controller combined with a new Simplified Direct Space Vector Modulation strategy (SDSVM), which is applied to the three-level NPC converter. This strategy is based on the use of a line-to-line three-level converter space vector diagram without using Park transformation and then simplifying it to that of a two-level converter. The performance of the proposed SDSVM technique in terms of controlling the three-level NPC-converter-based standalone WECS is demonstrated through simulation results. The whole WECS control and the SDSVM strategy are implemented on a dSPACE DS 1104 board that drives a DFIG-based wind system test bench. The obtained experimental results confirm the validity and performance in terms of control.

Emergence of the prosuming phenomenon inspired by environmental and financial incentives has led to a paradigm shift in energy markets and operational conditions of power distribution networks. As a result of this transition, Peer-to-Grid (P2G) and Peer-to-Peer (P2P) energy markets have received a lot of attention in recent years. These markets must prioritize the facilitation of fair and efficient energy trading while considering the preferences of both parties participating in these markets as well as Distribution System Operators (DSOs). In this context, ensuring the viability of the network's physical structure is essential. Without a robust physical structure, the energy trading process and the fulfillment of the parties'commercial obligations would be disrupted due to faults. Our proposed framework involves a fault-resilient energy management system in which P2G and P2P energy transactions are re-arranged based on factors such as the electrical distance of the dynamic physical route swept by P2P and P2G transactions and energy price. The electrical distance between end-users is calculated based on the dynamic configuration of the distribution network, which is adjusted due to the removal of faults and mitigation of emergencies such as line failures. In the developed framework, to reduce the overall operational cost of the community, an energy-sharing coordinator named Market Operator (MO) would then take into account the network configuration optimized by the Network Operator (NO). The obtained framework which joins the Network Re-configuration (NR) problem and the energy transactions re-arrangement problem in a hierarchical manner, is implemented on a 22-bus distribution system to evaluate its effectiveness in decreasing power losses and operational cost of grid-connected energy communities.

This paper presents a novel user-centered smart charging algorithm that follows different energy management scenarios for plug-in electric vehicles (PEVs) based on the user’s demand. The proposed approach consists of two separate stages: the model predictive control (MPC) with linear optimization and the rule-based fast method. This algorithm aims to reduce the total cost of energy exchanged with the grid from the user’s point of view while consuming the maximum photovoltaic (PV) power generation. In this regard, various scenarios are predicted and provided to the user in the form of charging costs and the state of health (SOH) of the PEV battery. Then, based on the user’s choices, the desired charging scenario is applied and the probable online small errors due to the other uncertainties are compensated. The effectiveness and flexibility of the proposed algorithm are evaluated through various simulation results for three PEVs at the same time. In addition, to provide further verification, the real-time part of the algorithm is executed in OPAL-RT simulator (OP5700) including the power hardware-in-the-loop (HIL) method.

In this paper, a new control coordination strategy is proposed to address multiple stability problems that may arise in HVAC/HVDC power systems. The stability issues studied in this paper include small-signal, rotor angle, frequency, and DC voltage. A benchmark composed of two 2-area AC systems inspired by Kundur system connected through a Modular Multilevel Converter-based (MMC) multi-terminal DC (MTDC) system is proposed to study multiple stability issues. To enhance the global security of the considered benchmark power system, supplementary power converter controllers are designed and implemented as ancillary HVDC services. The combination of these services may not always result in satisfactory dynamic performance due to system constraints and control interactions. Therefore, a coordinated strategy is proposed and evaluated through a comparative study. The advantages of this method are mainly: 1) AC & DC stability phenomena – usually studied separately – are considered and enhanced in a global approach, simultaneously, and 2) the coordination strategy guarantees minimal control interactions during operation without the need of modifying the tuning of the controller parameters.

The paper studies the stability issue in a multi-terminal HVDC grid where multiple vendors implement different control strategies for DC voltage regulation. Small-signal analysis reveals the effects of the droop gain values of two control options, with one showing better robustness than the other. The effects of the response time of the outer control loops as well as those of the DC reactors are also investigated. The results of the small-signal analysis are supported by EMT simulations.

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Electrical grids play a crucial role in the global energy transition by providing reliable energy transport. They must accommodate the integration of decentralized renewable energy systems (RESs), which vary in scale, generation rates, and intermittency. Ensuring this integration requires modern grids with enhanced performance and reliability. Today, various types of electrical grids are undergoing modernization, especially with the rise of electric vehicles. Traditional power grids are being equipped with advanced solutions across transmission, sub-transmission, and distribution networks. This modernization also extends to microgrids, high-voltage direct current (HVDC) systems, and wide-area synchronous grids, contributing to the emergence of new concepts such as supergrids and smart grids. This paper reviews rapidly the current state of research on electrical grids development, emphasizing critical concepts related to grids modernization and intellectualization. It aims to serve researchers, academics, and utility engineers interested in the latest advancements in the field. The aim of this work is unique and has not been addressed before, as the topics related to electrical grids are dispersed throughout the literature in large quantity, but they have not been reviewed as a cohesive whole.