The growing popularity of LVDC systems in the electrical industry is driving their evolution towards increasingly complex topologies, typically including several busbars and multiple load supply lines. In such complex environments, a reliable protection device selection process is becoming increasingly important. Recent contributions in DC fault analysis introduced methods which can accurately represent complex networks, overcoming the limitations of traditional approaches. In particular, methodologies based on equivalent circuits avoid the impractical requirement of modelling the entire grid in detail but are generally limited to simple grid topologies. This paper proposes an equivalent circuit model to approximate a selected portion of a DC network without restrictions on grid complexity or fault impedance, enabling an accurate representation of the grid dynamic response in the initial instants after a fault, which are, in most cases, of primary interest for protection purposes in this type of network. The results of a general case study demonstrate that the initial fault current response of a zone within a complex network including multiple busbars can be accurately represented under different fault conditions.

Traditional DC fault analysis approaches are effective primarily for cases involving very low-impedance faults or unusually simple systems, limiting their applicability. Recent advancements in DC fault analysis showed enhanced accuracy, flexibility, and are applicable to complex grid configurations and non-zero fault impedance scenarios. Nevertheless, these methods require to analyze the entire network for any fault to be considered, which can be impractical and computationally demanding. To address this issue, this paper explores the possibility of modeling a portion of an LVDC system by a simple RLC circuit, the parameters of which are determined by a straightforward analytical approximation relying on the main physical parameters of the whole DC grid. The proposed method produces a simple equivalent circuit, which is shown to reliably approximate the grid's fault behavior.

The Photovoltaic (PV) energy conversion is susceptible to fluctuations determined by the operating point of the cells employed. These variations in the output voltage impact the overall efficiency of the array when directly linked to the load. In this paper, the authors focus on a system that seamlessly integrates a renewable energy source, precisely a PV source, with the power system through a Non-Inverting Buck-Boost converter. To control the voltage, a sliding modebased nonlinear controller has been implemented to track the photovoltaic source at different power points. The proposed control strategy allows for fulfilling the voltage regulation requirements defined by the user from a SCADA in real-time. The proposed nonlinear controller has been modelled on Typhoon Hardware-inthe-Loop (HIL) Schematic Editor (2023) and simulated on Typhoon HIL SCADA (2023) to verify the performance of the designed framework. The results obtained from diverse simulation scenarios are presented, providing insights into the overall performance of the proposed system.

The increasing use of renewable energy sources and the rising adoption of self-consumption models is generating significant interest in DC networks. Compared to traditional AC systems, DC networks offer higher energy efficiency, by reducing the conversion losses, and optimal integration with photovoltaic systems and energy storage devices. However, the protection of DC networks presents unique challenges, including the absence of natural current zero-crossings and increased arc persistence. This paper explores various protection mechanisms for DC microgrids, focusing on their application in Collective Self-Consumption (CSC) contexts. Key protection strategies, based on mechanical switches, fuses, solid state circuit breakers, hybrid solutions and zonal architectures, are considered to ensuring safe, reliable, and efficient operation and to enhance the sustainability and energy independence of modern power systems. The analysis highlights the importance of adapting protection strategies to the specific requirements of DC microgrids intended for use in CSC applications, considering the grid complexity and the system reliability requirements.

This study proposes a novel data-driven consensus protocol for regulating the required oxygen excess ratio (OER) of multi-stack Proton Exchange Membrane Fuel Cell (PEMFC) systems, without requiring real-time state access or prior knowledge of the system dynamics. The control scheme incorporates a distributed state observer that predicts the states of each fuel cell by leveraging relative information from neighboring fuel cells. A consensus algorithm is then employed to enable each follower fuel cell to track the OER signal of the leader system. To optimize the consensus feedback gain, a direct data-driven optimal controller is designed, relying solely on leader system data. Furthermore, sufficient conditions for stability are derived from Lyapunov theorem and datadependent linear matrix inequalities solutions. The effectiveness of the proposed approach, along with the theoretical findings, are validated through numerical simulations, demonstrating robust performance under load variation and network uncertainties, including Deniel of Service and False Data injection attacks, with accurate tracking of the leader's outputs across all PEMFC stacks.

In recent years Power Quality (PQ) has been crucial in modern power systems, especially with the increasing integration of Renewable Energy Sources (RESs) and growing demand for electricity. Series Power Electronic Converters (SPECs) are one of the promising solutions for enhancing voltage quality at the Point of Common Coupling (PCC) in electrical distribution systems however, the performance of these devices is highly dependent on the accuracy of the synchronization techniques used. This paper is dedicated to evaluating the dynamic response of this device by using different synchronization techniques. Zero Crossing Detection (ZCD), Second-Order Generalized Integrator Single Phase Locked Loop (SOGI-SPLL), and All-Pass Filter Single Phase Locked Loop (APF-SPLL) are the techniques considered here. A comprehensive SPEC model is simulated in MATLAB/Simulink to check the system’s dynamical response, accuracy, and voltage PQ during transient conditions. These comparisons and findings highlight the importance of selecting appropriate synchronization techniques to optimize the performance of these systems in modern AC smart grids.

The correct modelling of a converter behaviour during fault events is essential for the accurate assessment of DC fault response and, in turn, for the proper selection of protection devices in DC networks. The circuit model conventionally used in the literature, while effective for many converter topologies, may lead to inaccurate predictions when applied to converters with output inductance. This paper identifies the limitations of the conventional model for this type of converters, particularly in estimating the fault current and its derived indicators, such as Joule integral, current slope and stored energy in the line inductance, which play a crucial role in the design of modern DC protection devices. In this paper, a revised modelling approach is proposed to capture the effect of the converter output inductance without increasing the overall model complexity. The proposed model is validated through simulations of a Buck converter connected to a DC network, demonstrating a high accuracy level in replicating line current, diode current and converter voltage waveforms. Comparative analysis shows that the proposed model provides more reliable estimates for protection indicators while maintaining computational efficiency.

The growing trend of on-site energy production, particularly through photovoltaic (PV) systems in apartment buildings and condominiums, presents a significant challenge: efficiently distributing the generated electricity amongst individual units. This study explores Self-Consumption Configurations for Renewable Energy Sharing in Condominiums (CACERs) as a solution to this hurdle and introduces a proposal model of power sharing as alternative model. This shift towards decentralized energy production aligns with the growing emphasis on empowering passive consumers. Recent European Directives highlight the importance of active end-user participation in the energy system, which includes residential, commercial, and tertiary buildings - substantial contributors to overall energy consumption. These “end-users” can become active participants either directly or through collaborative aggregations. To address the challenge of energy distribution within condominiums utilizing CACERs, this paper provides a comprehensive overview of the current state of CACERs in Italy. A case study of a typical urban condominium serves as the reference for this analysis. The study explores energy and economic assessments for the condominium, focusing on both the CACER and Power Sharing models. This analysis will provide valuable insights into the feasibility and benefits of these CACERs for condominiums in Italy.

In recent years, there has been increasing interest in integrating the smart grid concept into railway networks, which has been driven by the need to enhance energy efficiency and reduce air pollution in such energy-intensive systems. Consequently, experts have actively sought innovative solutions with which to tackle these challenges. One promising strategy involves integrating renewable energy sources (RESs), energy storage systems (ESSs), and electric vehicle charging stations (EVCSs) into current electric railway systems (ERSs). This study begins by examining the concept of implementing smart grids in railway systems through bibliometric analysis. It then delves into the realization of a hybrid railway microgrid (H-RMG) designed to enhance power flow capacities, improve energy efficiency, and address power quality issues in traditional AC railway networks. This paper introduces various future AC–DC-coupled hybrid railway microgrid (ADH-RMG) architectures centered around a shared DC bus acting as a DC hub for upgrading conventional AC railway systems utilizing interfacing static converters. Through an exploration of different possible ADH-RMG configurations, this research aims to offer valuable insights and a roadmap for the modernization and reconstruction of existing railway networks using smart grid technologies. The integration of RESs and EV charging infrastructures within the ADH-RMG concept presents a promising pathway toward establishing more sustainable and environmentally friendly railway systems.

Multiport converters (MCs) are widely adopted in many applications, from renewable energy sources and storage integration to automotive applications and distribution systems. They are used in order to interface different energy sources, storage devices and loads with one single, simple converter topology in contrast to the traditional approach, which can require different solutions made by two-port converters. MCs allow for a reduction in the number of components and cascaded conversion stages with respect to an equivalent system of two-port converters, resulting in reduced complexity, dimensions and costs, as well as in improved reliability and enhanced efficiency. Nevertheless, some aspects related to the design of MCs are still worth further discussion when MCs are applied to hybrid AC/DC distribution systems. First, most converters are developed for one specific application and are not modular in structure. Furthermore, many of the proposed solutions are not equally suitable for AC and DC applications and they can introduce significant issues in hybrid distribution systems, with earthing management being particularly critical. Even though most available solutions offer satisfying steady-state and dynamic performances, fault behavior is often not considered and the possibility of maintaining controllability during faults is overlooked. Building on these three aspects, in this paper, a new MC for hybrid distribution systems is presented. An innovative circuit topology integrating three-phase AC ports and three-wire DC ports and characterized by a unique connection between the AC neutral wire and the DC midpoint neutral wire is presented. Its control principles and properties during external faults are highlighted, and extensive numerical simulations support the presented discussion.

The integration of Artificial Intelligence (AI) in Energy Storage Systems (ESS) for Electric Vehicles (EVs) has emerged as a pivotal solution to address the challenges of energy efficiency, battery degradation, and optimal power management. The capability of such systems to differ from theoretical modeling enhances their applicability across various domains. The vast amount of data available today has enabled AI to be trained and to predict the behavior of complex systems with a high degree of accuracy. As we move towards a more sustainable future, the electrification of vehicles and integrating electric systems for energy storage are becoming increasingly important and need to be addressed. The synergy of AI and ESS enhances the overall efficiency of electric vehicles and plays a crucial role in shaping a sustainable and intelligent energy ecosystem. To the best of the authors’ knowledge, AI applications in energy storage systems for the integration of electric vehicles have not been explicitly reviewed. The research investigates the importance of AI advancements in energy storage systems for electric vehicles, specifically focusing on Battery Management Systems (BMS), Power Quality (PQ) issues, predicting battery State-of-Charge (SOC) and State-of-Health (SOH), and exploring the potential for integrating Renewable Energy Sources with EV charging needs and optimizing charging cycles. This study examined all topics to identify the most commonly used methods, which were analyzed based on their characteristics and potential. Future trends were identified by exploring emerging techniques introduced in recent literature contributions published since 2017.

Future electrical grids, particularly the distribution networks, may face more severe voltage rises/drops, and in general, more power quality problems in the presence of new loads such as electric vehicle chargers and renewable energy generation units like photovoltaic systems. This necessitates investing in additional high-cost infrastructure to increase the capability of the feeder in hosting higher levels of loads and generation units while the existing capacity is not utilized effectively. In the stated condition, effective voltage stabilization strategies in electrical distribution networks can contribute to hosting capacity improvement and the better utilization of the existing infrastructure. Accordingly, in this paper, the application of Open-UPQC in voltage profile improvement and hosting capacity enhancement is evaluated in low-voltage distribution networks. Furthermore, a dynamic reference voltage adjustment strategy is applied to the device to improve its capabilities in power quality improvement and hosting capacity enhancement. Simulation studies have been implemented to evaluate the capability of Open-UPQC either with static reference voltage or the dynamically-adjusted one in low-voltage networks with real measured data while different cases are assessed regarding the topology and the length of the feeder. The simulation results approved the capability of Open-UPQC especially with the dynamic reference voltage in hosting capacity enhancement while providing the highest level of voltage profile improvement among all the assessed custom power devices in the studied low-voltage networks.

Any industrial facility or manufacturing process must operate safely, effectively, and productively, so lighting devices are essential. They are the only source of illumination for activities that are confined to darkness and work continuously. On the other hand, facilities such as oil & gas, refineries and petrochemical plants must face and overcome the inherent difficulties of hazardous, as well as provide light. The energy savings from intelligent management of lighting systems, combined with the high degree of control that these solutions offer to the end-user and the possibility to schedule maintenance, make smart lighting technology the best candidate for the Ex lighting systems of the future. Therefore, smart lighting deserves proper attention and exploration, which is why this research was chosen.The Paper begins with a brief overview of lighting systems, followed by the theoretical foundations related to smart lighting systems. The research also includes a market analysis of major companies involved in smart lighting solutions, highlighting the need for reliable and safe lighting solutions that comply with industry standards.This paper contributes to the existing body of knowledge by providing a practical solution for smart lighting in various environments and particularly for Ex ambient.

The control of Proton Exchange Membrane Fuel Cell (PEMFC) is exceptionally challenging due to its complex nonlinearity, slow dynamics and load disturbance. In this paper, an Adaptive Model Free Control (AMFC) approach is introduced for regulating the PEMFC output voltage under load perturbation and measurement noise conditions. The proposed method consists of four sub-elements. Firstly, an Extended State Observer (ESO) based on a Single-Input Interval Type-2 Fuzzy intelligent PI (SI-IT-2-FLC-iPI) scheme is designed to enhance the performance of PEMFC. Secondly, a Nonlinear Sliding Mode Control-based Super Twisting Algorithm (NSMC-STA) is used as an auxiliary control approach to reduce the estimation error and ameliorate the system robustness. Thirdly, a Forgotten Recursive Least Square Error (FRLSE) is applied for adjusting the physical parameter of MFC and further ameliorating the control response. Finally, all these elements are merged together within what it is called Ultra Local Model (ULM). Through extensive simulation, the efficacy of the proposed regulator in accurately tracking the output signal is showcased, outperforming conventional controllers with remarkable improvements. The system achieves 0.001 steady-state error, 0% overshoot and settling time of approximately 8.9 s, which is good enough in the context of standalone fuel cell applications.

A systematic and responsible expansion of Low Voltage DC systems demands a thorough understanding of specific aspects of DC systems, such as protection systems, DC grids response to a fault, and fault identification and clearance, which are currently limiting the spread of DC distribution systems. For a preliminary evaluation the Traditional DC Fault Analysis method can be a useful tool for estimating fault current contributions from DC converters in LVDC networks during a fault. Unfortunately, its accuracy decreases when considering systems with multiple converters and non-negligible fault impedance. This limitation stems from the inherent assumptions in the analytical solution, resulting in: a) dependence on the reliability of results on fault impedance values and/or contributions from all fault currents of the other converters connected to the DC grid; b) inaccuracies of diode currents estimation, and c) inaccuracies in the Joule integral evaluation. These results may prove unreliable for designing protection systems for either a single converter or an entire network. Consequently, the aim of this work is to clearly identify these limits and to define Traditional DC Fault Analysis applicability in a complex network.

Protection devices play a crucial role in safeguarding LVDC grids, and their characteristics are strongly related to the grid design. Recently, significant emphasis has been placed on the design and selection of protective devices suitable for active DC grids. Depending on the technology used, protection devices have different breaking characteristics, impacting the power dissipated during a fault and thereby the sizing requirements of the different grid components. However, to achieve these outcomes, it is firstly necessary to accurately evaluate the DC grid fault current and voltage in any point in the grid and in different fault conditions. A preliminary estimation of fault current contributions can be addressed by the traditional DC fault analysis method only when the DC grids are simple and with few converters and/or for bolted faults because its accuracy significantly decreases when these conditions are not verified. As a result, a more accurate and flexible method to evaluate current and voltage with no restrictions on grid complexity or fault type would be highly beneficial, especially in the case of multiple converters and/or nonnegligible fault impedance. This paper discusses an innovative strategy for protection device selection in a generic LVDC grid. In particular, considering the different available technologies for DC circuit breakers, the main variables that can be used to trip protection devices are highlighted, and the effect of different technologies and settings on clearance times and relevant grid variables are discussed.

To ensure the power system operates optimally and economically, precise evaluations of component physical limitations are necessary. Hence, to evaluate these constrains, electrical grid operators usually adopt well-known methods based on mathematical model which better describe the physics behaviour of the system. An effective approach to estimate these limits is here presented employing Artificial Neural Network (ANN). With traditional methods, these estimations could be inaccurate due to many factors. Therefore, in this work an ANN based method to estimate all the working temperatures of overhead transmission lines has been presented. The estimation of the proposed ANN based method is compared to the CIGRE physical model. The case study results, based in real data, clearly show the great applicability and the improved accuracy of this proposed ANN based method.

DC smart grids are a promising solution for the efficient integration of renewable energy sources and loads. Still, their widespread adoption is hindered by significant challenges related to fault response, identification, and clearance. The traditional DC fault analysis method is a useful tool for straightforwardly understanding the behaviour of fault current contributions from DC converters in LVDC networks during a fault. However, when a system with multiple converters and non-negligible fault impedance need to be considered, its accuracy is severely limited due to the assumptions included in the problem solution, thus leading to the following: (a) the dependency of the results’ reliability on fault impedance values and/or other converter fault current contributions; (b) the inaccuracy of the diode current estimation; and (c) the inaccuracy of the conductor joule integral. Thus, these results’ data may be unreliable for designing protection systems for one converter or for an entire network. In order to overcome these issues, this paper proposes an innovative, simple numerical approach to DC fault current evaluation, which can be adopted when the number of converters become significant, or the network is complex. This method arises from the primary interest in solving the circuit to extract the indicators (current peak value and time, joule integral, etc.) necessary for designing circuit protections. This approach proved to grant two main advantages over traditional methods: (a) it provides accurate results, with no need to introduce any specific assumption; (b) it can be structured to manage an arbitrary number of converters; and (c) it reduces the computational processing times and resources necessary to simulate an entire DC network in comparison to other circuit solution software.

The paper presents an investigation of the applicability of controlled fault interruption techniques in radial, isolated, medium voltage distribution networks. In particular, when single phase-to-earth faults occur in isolated distribution systems, it is necessary to mitigate switching overvoltages. A comprehensive set of simulations has been carried out to evaluate the sensitivity of overvoltage phenomena to different switching strategies, with the aim of highlighting the possible methods to mitigate them and, thus, avoid harmful effects on electrical systems. The presented results show slight benefits in reducing overvoltages in the primary substation by independently controlling each pole of the switching device, regardless of the considered switching strategy. The inherent limitations of this approach are hence discussed, highlighting the current technological limitations, and alternative mitigation strategies are suggested.

Modern electrical distribution networks are prone to more severe voltage fluctuations due to the presence of variable loads such as electric vehicles and renewable energy generation units. These fluctuations decrease both the quality of power and the hosting capability of the grid. In such a condition, a Dynamic Voltage Compensator (DVC) can be used to stabilize the voltage of the LV networks. DVC is generally designed to resolve voltage fluctuations reflected from MV systems maintaining the voltage on a constant value. However, it will more effectively improve the voltage quality in the grid if the reference voltage is dynamically adjusted based on measurements inside the LV system. On the other hand, the more complex measurement and coordination strategy may lead to the inapplicability of the methods. Hence, voltage reference adjustment strategies should be developed to conform to the availability of data and measurements inside the grid. Accordingly, in this paper, novel voltage reference adjustment strategies have been developed for DVC based on the measurements at the installation point of the device. In order to examine the proposed methods, they are applied to an LV grid with real measured data and the results are discussed. Based on the provided simulation results, the developed dynamic reference voltage adjustment strategies can successfully improve the quality of voltage and improve the hosting capacity of the LV network.