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... Therefore, size and efficiency can be increased without compromising performance. However, unlike the AC system, the protection infrastructure for DC distribution must still be fully completed [20]. ...
... Load management, or demand-side management, is the remote monitoring and controlling of electrical consumption at multiple levels from sub-transmission to distribution [9,66]. The EMS system can perform the following functions: System load forecasting, unit commitment, economic dispatch, hydro-thermal scheduling, megawatts (MW) exchange evaluation, transmission loss minimization, security-constrained dispatch, maintenance scheduling, and production cost calculation [20,67]. Additionally, it ensures efficient maintenance and dispatch for neighboring systems. ...
... The control architecture of distributed multi-agent system (MAS) allows for the development of an innovative secondary compensating control technique. To further reduce the load variance and guarantee that the system is controlled with low voltage, digital average current sharing (DACS) management can be used [20,80,81]. ...
In 2022, the global electricity consumption was 4,027 billion kWh, steadily increasing over the previous fifty years. Microgrids are required to integrate distributed energy sources (DES) into the utility power grid. They support renewable and nonrenewable distributed generation technologies and provide alternating current (AC) and direct current (DC) power through separate power connections. This paper presents a unified energy management system (EMS) paradigm with protection and control mechanisms, reactive power compensation, and frequency regulation for AC/DC microgrids. Microgrids link local loads to geographically dispersed power sources, allowing them to operate with or without the utility grid. Between 2021 and 2028, the expansion of the world's leading manufacturers will be driven by their commitment to technological advancements, infrastructure improvements, and a stable and secure global power supply. This article discusses iterative, linear, mixed integer linear, stochastic, and predictive microgrid EMS programming techniques. Iterative algorithms minimize the footprints of standalone systems, whereas linear programming optimizes energy management in freestanding hybrid systems with photovoltaic (PV). Mixed-integers linear programming (MILP) is useful for energy management modeling. Management of microgrid energy employs stochastic and robust optimization. Control and predictive modeling (MPC) generates energy management plans for microgrids. Future microgrids may use several AC/DC voltage standards to reduce power conversion stages and improve efficiency. Research into EMS interaction may be intriguing.
... Reference [10] introduced the entropyindependent G1 method for weight calculation. Reference [11] introduced the concept of a smart energy hub, aiming to simplify system deployment. References [12,13] introduced the design of a microgrid in an isolated mode. ...
... where Equation (14) represents the objective function of the microgrid group, i.e., the sum of the objective functions of each sub-microgrid, corresponding to Equation (5). Equation (15) represents the equation constraint set of each sub-microgrid, corresponding to Equation (11). Equation (16) represents the inequality constraint set of each sub-microgrid, corresponding to Equations (12) and (13). ...
A microgrid cluster is composed of multiple interconnected microgrids and operates in the form of cluster, which can realize energy complementation between microgrids and significantly improve their renewable energy consumption capacity and system operation reliability. A microgrid optimal dispatch based on a distributed economic model predictive control algorithm is proposed in this paper. Firstly, the control task of the microgrid power generation system is defined, which is required to meet the load demand while reducing the economic loss of the system and realize dynamic economic optimization. The global objective function is designed based on the control task, and the detailed design method of the distributed economic model predictive controller is given. The control law is obtained by an iterative calculation using the Nash optimal method, which can effectively reduce the amount of data in the communication network. Finally, a microgrid group composed of four microgrids is used as an example for simulation verification. The simulation results show that the distributed economic model predictive control algorithm proposed in this paper has good economic benefits for microgrid dispatching.
... Internet of energy is a more generalized concept compared to smart grids, and involves thermal, chemical and electrical energies coordinated in wide area exploiting open-information data networks. Energy hubs [21], [24], [26]- [30], as building blocks for smart grids and internet of energy, have been the subject of many researchers' works during the past years. Some researches study high-level control and algorithms without specific concerns for the physical realization of the interconnections and converters [24], [26], [28], while others try to propose real structures of networks and converters of different forms of energy [21], [31]. ...
... Energy hubs [21], [24], [26]- [30], as building blocks for smart grids and internet of energy, have been the subject of many researchers' works during the past years. Some researches study high-level control and algorithms without specific concerns for the physical realization of the interconnections and converters [24], [26], [28], while others try to propose real structures of networks and converters of different forms of energy [21], [31]. Although the first group commonly regards the converters as black boxes, as illustrated in Figure 1.6, they still need some knowledge of internal interactions and phenomena of these black boxes, usually in the form of mathematical models to be able to design optimal control. ...
... Schematic diagram of a micro-grid[21]. ...
This work proposes a network architecture based on a generic converter structure as its core block, multi-port active-bridge (MAB) structure, for application in microgrids with renewable sources, energy storage devices, DC grids and AC grids. It starts with an introduction to the architecture and its characteristics. The potentials of clustering in enhancing efficiency, flexibility, and reliability of the system are discussed in the first chapter. Simulations are used to show that clustering and a global optimization strategy based on converter models are able to enhance the global system efficiency. The MAB structure, as the core block of the cluster converter, is the subject of a major part of this thesis.The second chapter starts by comparing the MAB topology to other topologies, and discussing the benefits of MAB converters in a cluster of converters. A MAB converter can simultaneously exchange energy between all sources and loads in either directions, while providing galvanic isolation between them. Its scalable and symmetric topology allows structured and modular optimization algorithms for modeling, design and control. Different models of MAB converters and power control methods are proposed. Additionally, a design procedure for MAB converters is presented.The third chapter continues the discussions on MAB converters. It starts by studying different types of losses in these converters and proposing loss models for different applications. Risk of saturation in magnetic of the transformer are explained. The origins of the DC currents in transformer windings, that cause saturation, are studied and solutions are presented. An innovative setup is proposed for measurement of DC currents along with experimental validation. Different voltage modulations for addressing DC link voltage variations that often occur in MAB converters are introduced and compared, using the loss model.A four-port 4×2 kW MAB converter prototype was designed and built in G2Elab. It was used for implementation and validation of the models and control schemes that were proposed in this work. Additionally, hardware-in-the-loop (HIL) validation was used as a first validation and as a quick and low-risk tool for solving potential issues in implementation of the embedded control. Different scenarios and operating points were tested on the prototype, comparing theoretical models, predictions and control methods against the experimental measurements. The results showed good conformities and certain nonconformities, all of which are discussed in detail.The final part of this work concludes that the proposed cluster of MAB converters is a promising solution for electrical network of microgrids. Studying MAB topology showed that it can be modeled and controlled in a scalable way, allowing for implementation of modular optimization modeling, design and control schemes in large scale clusters.
... Therefore, the BIC + DCT topology is more widely used than the BIC + ACT topology in the hybrid AC/DC microgrid [4]. ...
In small-scale hybrid AC/DC microgrid for residential applications, the CLLC-type resonant DC Transformer (DCT) is widely used because of its advantages of bidirectional power flow, electrical isolation, high efficiency, low cost and soft switching. However, single CLLC resonant converter has only one fixed output voltage, which makes it difficult to be compatible with most household appliances. In this paper, three-port resonant DCT has been proposed for residential applications. Resonant DCT operating modes has been analyzed in all scenarios. In order to make the converter work at its best efficiency, a method of frequency shift and phase shift control is used. Matlab / Simulink is used to verify the control of the output voltage in this way. The limitation and problem of the phase shift control in this topology has also been identified and discussed in the paper by experiment.
... Even with this distribution, the data to be handled can be very large. Therefore, the communication infrastructure should be able to support the increasing data volumes [4]. Also, With the growing number of smart energy devices that are being added to the smart grid network, the bandwidth requirement is continually increasing and should be considered in designing a reliable communication system that could deal with all mentioned challenges. ...
Growing the electrical and heat demand and increasing the need for the reliable and the cost-effective energy distribution systems facilitate using the multi-carrier energy distribution systems to supply demand. A multi-carrier energy network is a system that supports multiple types of energy carriers such as electricity, natural gas, and heat. This paper presents a new island-mode operation method for multi-carrier distribution systems where in case of the occurrence of a fault or critical event, the local network is disconnected from the main grid. This local network consisting of three energy hubs where the aim of these hubs is to supply their local energy demand with the minimum cost. For this purpose, the energy hubs decide to optimal scheduling of their resources and the optimal trading energy with other ones. To model such decision making framework, the Cournot competition model is employed in which the price of energy exchange among energy hubs is modeled based on the Time-Of-Use demand response program. This model is mathematically solved using Karush–Kuhn–Tucker conditions. For this purpose, these conditions are applied on the optimization problem of all hubs, simultaneously. To show the effectiveness of the model, it is applied on a test case with three hubs. The results show the optimal behavior of the hubs in such framework to minimize their operation cost.
In recent years, research has shown a growing interest in the use of hybrid wind photovoltaic (PV) systems that provide better performance compared to the use of a single component due to complementarity in meeting electricity demand. Over the past twenty-five years, hundreds of articles have addressed the topic of hybrid systems considering different configurations and final uses and, over the past decades, many reviews have made a comprehensive summary of various results obtained. However, some reviews deal with the research in a too general and qualitative way, without providing quantitative data, and other reviews are too focused on a specific topic aspect. To provide a qualitative-quantitative prospect of the research trend in the last twenty-five years, the present work is aimed at carrying out a literature review and statistical analysis starting from data extracted from the 550 most relevant and recent articles concerning hybrid systems, published between 1995 and 2020. The review aim was to produce an upgradable matrix literature database that schematizes the content of all articles in terms of different categories, such as the geographical distribution, their component configurations, operating mode and the auxiliary components used to support it, their intended uses and study methodologies (simulation, experimental, economic, energy, environmental and social analysis etc.) and software used. In addition, all the optimization algorithm, energy, economic, environmental and social indicators available in the literature were extracted and elaborated to identify the most used. The 550 articles were analysed, compared, and classified into several categories to provide an overall framework of the state of the art. The objective is to clearly and appropriately show important trends and findings in the development of hybrid wind and solar PV experimental, simulation and optimization projects. Data are elaborated to obtain a statistical analysis for each category or a combination of categories. In particular, the analysis highlighted that research is more focused on testing systems in warm or temperate localities, with the Köppen climate groups B and C prevalent over the others. From the geographical point of view, Asia is the continent most involved in world research (with China, India and Iran the first three countries for total publications produced). However, also in other parts of the world, a growing interest was noticed in this technology. The prevalent tested system configuration mode is the stand-alone hybrid systems, in a wide variety of climates and especially for residential uses. Simulations are mostly implemented in the analysed publications, mainly through HOMER and MATLAB software. Parametric analysis is widely used for optimal system design with a large variety of techniques. In particular, the system performance is examined mostly from an energy point of view. Economic analysis is also very common, alone or in combination with energy analysis. The most frequently used optimization algorithms are the particle swarm optimization (PSO) and genetic algorithm (GA), while the loss of power supply probability (LPSP) and renewable fraction (RE) for the energy analysis, the net present cost (NPC) and cost of energy (COE) for the economic analysis and the emissions (E) of CO2 for the environmental analysis are most widespread indicators. Finally, an analysis on the size of the system components is performed to study which renewable source is more preferred at low and high installed power, for stand-alone, grid-connected systems and overall, considering different intended uses. The analysis highlights that PV systems are preferred at low installed powers, especially for residential use and stand-alone mode, while wind systems, in addition to being extensively used for low installed powers, demonstrates higher employment compared to PV systems as the power increases. The paper findings and upgradable matrix literature database are proposed as a valuable tool for engineers, experts and national and international policymakers.
Energy supply is one of the main challenges of the present century. Population growth, rising energy demand, fossil fuel scarcity, and environmental concerns have made energy security as major issue for all countries in the world. Traditional power system, including low-efficiency generation, long-distance transmission and then a complex distribution system, face various challenges that make it inappropriate as a future secure energy system.
Today, the energy hub as a framework of generation, conversion, storage and consumption of different energy carriers, is considered by many researchers as the prospect of a future secure energy system.
