• Energy Research

In the future energy system, a new energy market design and framework is required to incentivize a high share of prosumers, who consume, store, and produce energy. In order to support active prosumers, the European Union (EU), in directives of Clean Energy for all Europeans package, provides the basic requirements to form an energy community (EC). However, this package does not include any particular architecture. In this regard, this paper will review the main articles of the EU directives in terms of the EC and investigate the EC structure suggested by Finnish regulation to identify the barriers of forming an optimum EC. Finally, this paper proposes an efficient structure to form a local market based on a virtual energy community using the existing grid operators.

The massive deployment of electrical vehicles (EV) creates new challenges and some opportunities for power systems. This paper focuses on the potential of EV charging stations to provide flexibility for electrical grids. Since there is no concrete definition for flexibility in power systems, this paper first looks at the market opportunity for flexibility and then proposes a method to calculate the flexibility of EV based on the market definition. Then, the flexibility of EV is derived from data collected from charging stations in the Helsinki area between 2015 and 2018.

Poussée par des aspects environnementaux et économiques, la prolifération des sources d'énergie renouvelables (SER) a été étendue dans les systèmes électriques du monde entier. À cet égard, la production intermittente de ces SER (par exemple, les parcs photovoltaïques et éoliens) peut causer plusieurs problèmes opérationnels et de stabilité dans ces systèmes électriques à faible inertie. Pour gérer ces problèmes, un grand intérêt dans la littérature a été dirigé vers le développement de schémas de contrôle des convertisseurs de source de tension (VSC) réalisables formant un réseau qui ont des fonctions de régulation de tension/fréquence. Par conséquent, un examen complet est présenté dans ce document pour ces schémas de contrôle VSC de formation de grille prometteurs qui seront l'épine dorsale des systèmes d'alimentation durables dominés par les convertisseurs. Spécifiquement, les structures de contrôle, les fonctionnalités de support de réseau intelligent, les problèmes de stabilité et les atténuations de courant de défaut sont comparés en tenant compte des schémas de contrôle VSC de formation de grille existants. De plus, les applications de VSC de formation de grille ainsi que leurs avantages et inconvénients sont étudiés pour les systèmes d'alimentation isolés et en vrac. Les aspects d'évaluation sont également explorés pour évaluer la performance des schémas de contrôle VSC existants dans le réseau. Enfin, les défis actuels auxquels sont confrontés VSC dans les applications à venir et les lacunes existantes sont mis en évidence tout en correspondant des perspectives pour de futures études de recherche sont définies pour des systèmes électriques stables et durables à faible inertie. Impulsado por aspectos ambientales y económicos, la proliferación de fuentes de energía renovables (FER) se ha expandido en los sistemas de energía en todo el mundo. En este sentido, la generación intermitente de dichas FER (por ejemplo, parques fotovoltaicos y eólicos) puede causar varios problemas operativos y de estabilidad en dichos sistemas de energía de baja inercia. Para manejar estos problemas, se ha dirigido un gran interés en la literatura para desarrollar esquemas de control de convertidores de fuente de tensión (VSC) formadores de red viables que tengan funciones reguladoras de tensión/frecuencia. En consecuencia, se presenta una revisión inclusiva en este documento para estos prometedores esquemas de control de VSC formadores de red que serán la columna vertebral de los sistemas de energía sostenibles dominados por convertidores. Específicamente, las estructuras de control, las funcionalidades de soporte de red inteligente, los problemas de estabilidad y las mitigaciones de corriente de falla se comparan considerando los esquemas de control de VSC formadores de red existentes. Además, las aplicaciones de VSC formadores de red junto con sus beneficios e inconvenientes se investigan para los sistemas de energía aislados y a granel. Los aspectos de evaluación también se exploran para evaluar el rendimiento de los esquemas de control de VSC existentes en la red. Finalmente, los desafíos actuales que enfrenta VSC en las próximas aplicaciones y las brechas existentes se resaltan mientras corresponden se definen perspectivas para futuros estudios de investigación para sistemas de energía de baja inercia sostenibles y estables. Driven by environmental and economic aspects, the proliferation of renewable energy sources (RES) has been expanded in power systems worldwide.In this regard, the intermittent generation of such RESs (e.g., photovoltaic and wind farms) can cause several operational and stability problems in such lowinertia power systems.To handle these issues, great interest in the literature has been directed to develop feasible grid-forming voltage source converters (VSC) control schemes that have voltage/frequency regulatory functions.Accordingly, an inclusive review is presented in this paper for these promising gridforming VSC control schemes which will be the backbone of sustainable converter-dominated power systems.Specifically, control structures, smart grid-support functionalities, stability issues, and fault current mitigations are compared considering the existing grid-forming VSC control schemes.Besides, the applications of grid-forming VSC along with their benefits and drawbacks are investigated for both isolated and bulk power systems.The evaluation aspects are also explored for assessing the performance of the existing VSC control schemes in the grid.Finally, the current challenges that face VSC in forthcoming applications and existing gaps are highlighted while corresponding perspectives for future research studies are defined for stable sustainable low-inertia power systems. مدفوعًا بالجوانب البيئية والاقتصادية، تم توسيع انتشار مصادر الطاقة المتجددة (RES) في أنظمة الطاقة في جميع أنحاء العالم. في هذا الصدد، يمكن أن يتسبب التوليد المتقطع لهذه المصادر (على سبيل المثال، مزارع الطاقة الكهروضوئية والرياح) في العديد من مشاكل التشغيل والاستقرار في أنظمة الطاقة منخفضة القصور الذاتي هذه. للتعامل مع هذه المشكلات، تم توجيه اهتمام كبير بالأدبيات لتطوير مخططات تحكم في محولات مصدر الجهد لتشكيل الشبكة (VSC) ذات وظائف تنظيمية للجهد/التردد. وفقًا لذلك، يتم تقديم مراجعة شاملة في هذه الورقة لمخططات التحكم VSC الواعدة لتشكيل الشبكة والتي ستكون العمود الفقري لأنظمة الطاقة التي يهيمن عليها المحول المستدام. على وجه التحديد، تتم مقارنة هياكل التحكم ووظائف دعم الشبكة الذكية وقضايا الاستقرار والتخفيف من تيار الأعطال مع الأخذ في الاعتبار مخططات التحكم VSC الحالية لتشكيل الشبكة. إلى جانب ذلك، يتم التحقيق في تطبيقات VSC لتشكيل الشبكة إلى جانب فوائدها وعيوبها لكل من أنظمة الطاقة المعزولة والسائبة. كما يتم استكشاف جوانب التقييم لتقييم أداء مخططات التحكم VSC الحالية في الشبكة. أخيرًا، يتم تسليط الضوء على التحديات الحالية التي تواجه VSC في التطبيقات القادمة والفجوات الحالية أثناء المقابلة يتم تعريف وجهات نظر الدراسات البحثية المستقبلية لأنظمة طاقة منخفضة القصور الذاتي مستقرة ومستدامة.

The European Green Deal targets to increase significantly the share of renewable energy sources (RES) in the electricity system by 2030. However, the electricity market is a competed sector and the private investors develop RES capacity based on the profitability of the business plan. The RES profitability depends strongly on the long-term future price of the electricity market, which needs to be estimated. Although several studies focus on developing accurate short-time forecasting methods for the day-ahead market, these methods cannot be used for long-term forecasting due to uncertainty of the required inputs, e.g. weather condition and fuel cost, in a long-term future. In these circumstances, this paper developed a methodology to analyse and estimate the long-term day-ahead electricity market. This research used the data of Finnish electricity market to show the performance of the methodology. However, the same methodology could also be applied to other countries.

High penetration of renewable energy sources (RESs) in distribution systems leads to reverse active power and voltage rise in low voltage (LV) grids, which limits the hosting capacity. Energy storage systems (ESSs) have been used to improve the hosting capacity by decreasing the reverse active power in some literature. ESSs can still improve the hosting capacity more by providing reactive power. The reactive power shows a little effect in existing researches, because they have mostly simulate LV grids without modeling transformers. However, the high reactance of the transformer magnifies the effectiveness of the reactive power control even more than the active power in some buses. This paper develops an optimal method for placement, sizing, and active and reactive power control of a central ESS to improve the hosting capacity. The simulation results in highly RES penetrated grids at Germany show the effectiveness of the proposed method.

Worst-case excess minimization provides a stabilizing value sharing mechanism for energy communities (ECs). It, however, takes much time to solve the problem especially in larger ECs with tens of prosumers. To alleviate the issue, this paper proposes a modified worst-case excess minimization problem which is faster to solve. In this paper, the problem is formulated for individual time slots, e.g., hour by hour, instead of solving the problem for the whole study horizon. This enables modifying the problem by defining new constraints as well as removing unnecessary variables and constraints. By doing so, the minimization problem can be solved faster without sacrificing the accuracy of the simulation. The proposed method is simulated, and the achieved results are compared with the original worst-case excess minimization problem. Based on the results, the proposed method performed significantly better than the original.

Energy community creates value by aggregating the demand and supply profiles of neighbouring prosumers. The value must be shared fairly while not discouraging new members from joining the energy community. This paper presents an approach for modelling the value of energy community as well as several value sharing methods. A model energy community is simulated based on a yearlong historical data of six household prosumers. The energy community was investigated in terms of self-sufficiency, self-consumption and value cause distribution. The case study highlighted the drawbacks of conventional value sharing methods. An adjusted marginal contribution or Shapley methods are suggested to provide most fair and practical value distribution.