• Energy Research

With the rapid development of modern energy applications such as renewable energy, PV systems, electric vehicles, and smart grids, DC-DC converters have become the key component to meet strict industrial demands. More advanced converters are effective in minimizing switching losses and providing an efficient energy conversion; nonetheless, the main challenge is to provide a single converter that has all the required features to deliver efficient energy for different types of modern energy systems and energy storage system integrations. This paper reviews multilevel, bidirectional, and resonant converters with respect to their constructions, classifications, merits, demerits, combined topologies, applications, and challenges; practical recommendations were also made to deliver clear ideas of the recent challenges and limited capabilities of these three converters to guide society on improving and providing a new, efficient, and economic converter that meets the strict demands of modern energy system integrations. The needs of other industrial applications, as well as the number of used elements for size and weight reduction, were also considered to achieve a power circuit that can effectively address the identified limitations. In brief, integrated bidirectional resonant DC-DC converters and multilevel inverters are expected to be well suited and highly demanded in various applications in the near future. Due to their highlighted merits, more studies are necessary for achieving a perfect level of reducing losses and components.

With the proliferation of large-scale grid-connected wind farms, subsynchronous oscillation (SSO) incidents associated with Type-4 wind turbines (WTs) with a permanent magnet synchronous generator (PMSG) have occurred frequently. These incidents have caused severe reliability risks to the power grid. Conventionally, P-Q capability charts are utilized to ensure the safety operating region of a synchronous generator. However, a PMSG WT exhibits completely different and dynamic P-Q capability characteristics due to the difference in energy conversion technique and several critical factors related to the WT power converters. This paper presents a comprehensive dynamic P-Q capability study of a PMSG WT with sufficient and accurate considerations of the WT control and operation in the dq reference frame, its power converter constraints, and grid dynamics. Models of a PMSG WT are first developed based on its control principle in the dq reference frame. Then, algorithms for obtaining the P-Q capability charts of the WT are developed with the considerations of complete WT constraints in different aspects. The study analyzes the root cause of many abnormal operations of grid-connected PMSG WTs, reported in the literature, from the dynamic P-Q capability perspectives. The proposed study is verified via an electromagnetic transient (EMT) model of a grid-connected Type-4 WT.

Une pile à combustible (FC) est l'une des solutions les plus viables à la crise énergétique actuelle et au problème de pollution de l'environnement. Il peut être appliqué dans la production d'énergie, l'alimentation électrique portable, ainsi que dans les véhicules hybrides. En raison de la nature polyvalente de cette source d'énergie et de la non-dépendance aux conditions environnementales, les FC peuvent être une source importante de source d'énergie alternative à l'avenir. Les chercheurs travaillent sur les topologies de conversion de puissance et le développement de stratégies de contrôle pour les applications FC au cours de la dernière décennie. Cependant, le dernier résumé des progrès dans ce secteur n'est pas disponible dans la littérature. Cet article vise à discuter des différentes techniques de contrôle et des systèmes de gestion de l'énergie rapportés dans la littérature. Les configurations sont classées en fonction de leur nature, de leur domaine d'application et de leurs performances. Différentes stratégies de gestion de l'énergie utilisées dans les systèmes à base de piles à combustible sont considérées ici pour l'analyse qualitative. Les caractéristiques essentielles telles que les avantages, les inconvénients et les possibilités d'amélioration des diverses stratégies de gestion de l'énergie des véhicules à pile à combustible sont discutées du point de vue du système de contrôle. Enfin, les tendances récentes dans le développement de systèmes hybrides de gestion de l'énergie à pile à combustible sont présentées pour améliorer les performances sur la base de l'analyse qualitative ci-dessus. Cet article aidera les chercheurs dans ce domaine à connaître l'état actuel, les tendances futures et les futures orientations de la recherche sur les piles à combustible pour la production d'électricité. Una pila de combustible (FC) es una de las soluciones más viables a la crisis energética actual y al problema de la contaminación ambiental. Se puede aplicar en generación de energía, fuente de alimentación portátil, así como en vehículos híbridos. Debido a la naturaleza versátil de esta fuente de energía y a la no dependencia de las condiciones ambientales, las FC pueden ser una fuente importante de energía alternativa en el futuro. Los investigadores están trabajando en topologías de conversión de potencia y desarrollo de estrategias de control para la aplicación de FC durante la última década. Sin embargo, el último resumen de los avances en este sector no está disponible en la literatura. Este artículo tiene como objetivo discutir las diversas técnicas de control y sistemas de gestión de energía reportados en la literatura. Las configuraciones se clasifican según su naturaleza, área de aplicación y rendimiento. Las diferentes estrategias de gestión de la energía utilizadas en los sistemas basados en pilas de combustible se consideran aquí para el análisis cualitativo. Las características esenciales, como las ventajas, desventajas y oportunidades de mejora de diversas estrategias de gestión energética de los vehículos de pila de combustible, se discuten desde el punto de vista del sistema de control. Finalmente, se presentan las tendencias recientes en el desarrollo de sistemas de gestión de energía híbridos de pila de combustible para mejorar el rendimiento en función del análisis cualitativo anterior. Este artículo ayudará a los investigadores en este campo a conocer el estado actual, la tendencia futura y las futuras direcciones de investigación en la investigación de celdas de combustible para la generación de energía. A fuel cell (FC) is one of the most viable solutions to the current energy crisis and environmental pollution problem. It can be applied in power generation, portable power supply, as well as in hybrid vehicles. Due to the versatile nature of this energy source and non-dependency over the environmental conditions, FCs can be a significant source of alternative energy source in the future. Researchers are working on power conversion topologies and control strategies development for FC application for the past decade. However, the latest summary of the progress in this sector is not available in the literature. This article is aimed at discussing the various control techniques and energy management systems reported in the literature. The configurations are categorized according to their nature, application area, and performance. Different energy management strategies used in fuel cell-based systems are considered here for the qualitative analysis. The essential characteristics such as the advantages, disadvantages, and improvement opportunities of various energy management strategies of fuel cell vehicles are discussed from the control system point of view. Finally, the recent trends in the development of fuel cell hybrid energy management systems are presented to improve the performance based on the above qualitative analysis. This article will help the researchers in this field to know the current status, future trend and the future research directions in fuel cell research for power generation. خلية الوقود (FC) هي واحدة من أكثر الحلول قابلية للتطبيق لأزمة الطاقة الحالية ومشكلة التلوث البيئي. يمكن استخدامه في توليد الطاقة، وإمدادات الطاقة المحمولة، وكذلك في المركبات الهجينة. نظرًا للطبيعة المتنوعة لمصدر الطاقة هذا وعدم الاعتماد على الظروف البيئية، يمكن أن تكون FCs مصدرًا مهمًا لمصدر الطاقة البديلة في المستقبل. يعمل الباحثون على طوبولوجيا تحويل الطاقة وتطوير استراتيجيات التحكم لتطبيق FC على مدى العقد الماضي. ومع ذلك، فإن أحدث ملخص للتقدم المحرز في هذا القطاع غير متوفر في الأدبيات. تهدف هذه المقالة إلى مناقشة تقنيات التحكم المختلفة وأنظمة إدارة الطاقة الواردة في الأدبيات. يتم تصنيف التكوينات وفقًا لطبيعتها ومنطقة التطبيق والأداء. يتم النظر هنا في استراتيجيات إدارة الطاقة المختلفة المستخدمة في الأنظمة القائمة على خلايا الوقود للتحليل النوعي. تتم مناقشة الخصائص الأساسية مثل مزايا وعيوب وفرص التحسين لاستراتيجيات إدارة الطاقة المختلفة لمركبات خلايا الوقود من وجهة نظر نظام التحكم. أخيرًا، يتم عرض الاتجاهات الحديثة في تطوير أنظمة إدارة الطاقة الهجينة لخلايا الوقود لتحسين الأداء بناءً على التحليل النوعي أعلاه. ستساعد هذه المقالة الباحثين في هذا المجال على معرفة الوضع الحالي والاتجاه المستقبلي واتجاهات البحث المستقبلية في أبحاث خلايا الوقود لتوليد الطاقة.

The increase in penetration levels of inverter-based resources (IBRs) is changing the dynamic performance of power grids of different parts of the world. IBRs are now being more and more integrated into the grid at a single connection point as an IBR plant. Due to the complex nature and dynamicity of each inverter model, it is not realistic to build and analyze full complex models of each inverter in the IBR plant. Moreover, simulating a large plant including detailed models of all the IBRs would require high computing resources as well as a long simulation time. This has been the main issue addressed in the new IEEE Std 2800-2022. This paper proposes a novel approach to model an IBR plant, which can capture the transient nature at the plant level, detailed IBR control at the inverter level, interactions of multiple IBR groups in a plant structure, and a collector system connecting the IBRs to the grid. The IBRs in the plant use a voltage source inverter topology combined with a grid-connected filter. The control structure of the IBR includes a cascaded loop control where an inner current control and outer power control are designed in the dq-reference frame, and a closed-loop phase-locked loop is used for the grid synchronization. The mathematical study is conducted first to develop aggregated plant models considering different operating scenarios of active IBRs in an IBR plant. Then, an electromagnetic transient simulation (EMT) model of the plant is developed to investigate the plant’s dynamic performance under different operating scenarios. The performance of the aggregated plant model is compared with that of a detailed plant model to prove the effectiveness of the proposed strategy. The results show that the aggregated EMT simulation model provides almost the same result as the detailed model from the plant perspective while the running time/computation burden is much lower.

Electric vehicle grid integration (EVGI) is one of the most important parts of transportation electrification. However, large-scale EV charging/discharging can have an adverse effect on the distribution grid, due to a large amount of load being drawn from or fed back to the power grid. Additionally, the power electronics used in the grid interaction may impose additional complications, such as voltage and frequency deviation, harmonic distortion, etc. With proper control scheme designs for the grid-connected inverters, such complications can be mitigated, and several grid ancillary services, such as voltage and frequency support, reactive power support, and harmonic mitigation, can be facilitated from large-scale EVGI. In this study, a large-scale EVGI system is developed where the vector control implementation of a grid-connected inverter in the d-q reference frame is presented for providing different grid ancillary services using the EVGI system. The EVGI system is operated in different control modes to ensure multiple ancillary services of the power grid. The study is supported by the electromagnetic transient simulation performed in Matlab/Simulink of a large-scale EVGI system. The simulation shows that with the proper control mechanism of grid-connected inverters, EVGI can be used to provide several useful grid ancillary services.

Abstract Due to the rapid development in modern power industrial applications such as renewable energy, photovoltaic, laptop adapters and electric vehicles, DC/DC resonant converters have gained the attention of many researchers. The rise of the potential of this industry has since led to a plethora of studies on resonant converter topologies with the aim to enhance the features of soft switching, high power density, smooth waveforms and high efficiency. The efficiency of these converters has been proven, thus are undoubtedly favored over hard switching conventional converters because of their ability to both work at high frequency and reduce switching losses. Researches are still being continued to significantly reduce the cost and number of components, besides improving areas such as high power density, high efficiency, wide load variations, and reliability. This paper presents the principles of resonant power converters (RPCs) and their classifications based on their DC-DC converter family, and ability to achieve soft switching. Several recent research trends have focused on the development of their constructions, operational principles, merits and demerits. The study of different resonant DC–DC converter topologies suggests that there is no single topology which can achieve all requirements. Therefore, further research is required to produce a power circuit that can eliminate the addressed limitations as many as possible.