Analysis of measures to increment the share of renewable energy in distribution grids

The actual power system is undergoing a period of transformation. The introduction of renewable energy power parks in the grid started the transition from a high voltage connected generation model towards a model where part of the generation assets will be connected to medium and even low voltage grids. Furthermore, the fast-changing world of technology is starting to allow passive users to generate and manage electricity, and thus, take a new position towards the grid. This transformation entails new opportunities and challenges for a power system that was initially thought to be vertically integrated and with unidirectional power flows. Europe is already giving its directives to ease the transition towards a more decentralized power system; however, some member states are faster than others when transposing them. Taking advantage of the different speeds between member states, this thesis aims to analyse and compare those pioneering regulatory frameworks in terms of renewable energy sources connection to distribution grids. This should allow the thesis to identify which kind of measures are the best ones to increase the share of renewable energy sources. In order to carry out the research, a systematic review of technical and energy policy articles has been carried out consulting the ScienceDirect, the IEEE Xplore, and the ResearchGate databases, together with European directives and regulations in the field of energy policies and member states network codes for connection of generation assets. The core of the thesis is based on a few institutions and documents which we would like to highlight. To set the technical basis of the impact of renewable energy sources, the book Integration of Distributed Generation in the Power System has been used. In terms of conceptualizing the regulatory framework the Florence School of Regulation technical reports The EU Electricity Network Codes and the Clean Energy Package are essential to this thesis together with the European energy e-Directive and e-Regulation. The report The smartEn Map: European Balancing Markets Edition (2018) published by smartEn has been used as a reference point to study the state of the art of balancing markets. Finally, the network codes for Low Voltage Grid Connection of Generators from Italy, Germany and Denmark are the base for the development of the energy storage section. The European directives and regulations point towards a market-based approach to overcome the challenges and benefit from the opportunities that the transition towards a distributed power system will create. The thesis go from a holistic view, considering the new European guidelines, to a study of those member states that are already half-way on their transition towards a distributed power system based on renewable energy sources. This is will give an overview of the current regulatory framework and find the main outlines of the forthcoming one. Finally, comment that one of the outcomes of the research carried out during the thesis is the participation in the conference paper "RESOlvD: ICT services and energy storage for increasing renewable hosting capacity in LV distribution grids". The paper has been approved for publication, and it can be partially consulted in the Annex A of the thesis

Ten questions concerning integrating smart buildings into the smart grid

Recent advances in information and communications technology (ICT) have initiated development of a smart electrical grid and smart buildings. Buildings consume a large portion of the total electricity production worldwide, and to fully develop a smart grid they must be integrated with that grid. Buildings can now be ‘prosumers’ on the grid (both producers and consumers), and the continued growth of distributed renewable energy generation is raising new challenges in terms of grid stability over various time scales. Buildings can contribute to grid stability by managing their overall electrical demand in response to current conditions. Facility managers must balance demand response requests by grid operators with energy needed to maintain smooth building operations. For example, maintaining thermal comfort within an occupied building requires energy and, thus an optimized solution balancing energy use with indoor environmental quality (adequate thermal comfort, lighting, etc.) is needed. Successful integration of buildings and their systems with the grid also requires interoperable data exchange. However, the adoption and integration of newer control and communication technologies into buildings can be problematic with older legacy HVAC and building control systems. Public policy and economic structures have not kept up with the technical developments that have given rise to the budding smart grid, and further developments are needed in both technical and non-technical areas

Stochastic management framework of distribution network systems featuring large-scale variable renewable energy sources and flexibility options

The concerns surrounding climate change, energy supply security and the growing demand are forcing changes in the way distribution network systems are planned and operated, especially considering the need to accommodate large-scale integration of variable renewable energy sources (vRESs). An increased level of vRESs creates technical challenges in the system, bringing a huge concern for distribution system operators who are given the mandate to keep the integrity and stability of the system, as well as the quality of power delivered to end-users. Hence, existing electric energy systems need to go through an eminent transformation process so that current limitations are significantly alleviated or even avoided, leading to the so-called smart grids paradigm. For distribution networks, new and emerging flexibility options pertaining to the generation, demand and network sides need to be deployed for these systems to accommodate large quantities of variable energy sources, ensuring an optimal operation. Therefore, the management of different flexibility options needs to be carefully handled, minimizing the sideeffects such as increasing costs, worsening voltage profile and overall system performance. From this perspective, it is necessary to understand how a distribution network can be optimally operated when featuring large-scale vRESs. Because of the variability and uncertainty pertinent to these technologies, new methodologies and computational tools need to be developed to deal with the ensuing challenges. To this end, it is necessary to explore emerging and existing flexibility options that need to be deployed in distribution networks so that the uncertainty and variability of vRESs are effectively managed, leading to the real-time balancing of demand and supply. This thesis presents an extensive analysis of the main technologies that can provide flexibility to the electric energy systems. Their individual or collective contributions to the optimal operation of distribution systems featuring large-scale vRESs are thoroughly investigated. This is accomplished by taking into account the stochastic nature of intermittent power sources and other sources of uncertainty. In addition, this work encompasses a detailed operational analysis of distribution systems from the context of creating a sustainable energy future. The roles of different flexibility options are analyzed in such a way that a major percentage of load is met by variable RESs, while maintaining the reliability, stability and efficiency of the system. Therefore, new methodologies and computational tools are developed in a stochastic programming framework so as to model the inherent variability and uncertainty of wind and solar power generation. The developed models are of integer-mixed linear programming type, ensuring tractability and optimality.As mudanças climáticas, a crescente procura por energia e a segurança de abastecimento estão a modificar a operação e o planeamento das redes de distribuição, especialmente pela necessidade de integração em larga escala de fontes de energia renováveis. O aumento desses recursos energéticos sustentáveis gera enormes desafios a nível técnico no sistema, atendendo a que o operador do sistema de distribuição tem o dever de manter a integridade e a estabilidade da rede, bem como a qualidade de energia entregue aos consumidores. Portanto, os sistemas de energia elétrica existentes devem passar por um eminente processo de transformação para que as limitações atuais sejam devidamente atenuadas ou mesmo evitadas, esperando-se assim chegar ao paradigma das redes elétricas inteligentes. Para as redes de distribuição acomodarem fontes variáveis de energia renovável, novas e emergentes opções de flexibilidade, que dizem respeito à geração, carga e à própria rede, precisam de ser desenvolvidas e consideradas na operação ótima da rede de distribuição. Assim, a gestão das opções de flexibilidade deve ser cuidadosamente efetuada para minimizar os efeitos secundários como o aumento dos custos, agravamento do perfil de tensão e o desempenho geral do sistema. Desta perspetiva, é necessário entender como uma rede de distribuição pode operar de forma ótima quando se expõe a uma integração em larga escala de fontes variáveis de energia renovável. Devido à variabilidade e incerteza associadas a estas tecnologias, novas metodologias e ferramentas computacionais devem ser desenvolvidas para lidar com os desafios subsequentes. Desta forma, as opções de flexibilidade existentes e emergentes devem ser implantadas para gerir a incerteza e variabilidade das fontes de energia renovável, mantendo o necessário balanço entre carga e geração. Nesta tese é feita uma análise extensiva das principais tecnologias que podem providenciar flexibilidade aos sistemas de energia elétrica, e as suas contribuições para a operação ótima dos sistemas de distribuição, tendo em consideração a natureza estocástica dos recursos energéticos intermitentes e outras fontes de incerteza. Adicionalmente, este trabalho contém investigação detalhada sobre como o sistema pode ser otimamente gerido tendo em conta estas tecnologias de forma a que a uma maior percentagem de carga seja fornecida por fontes variáveis de energia renovável, mantendo a fiabilidade, estabilidade e eficiência do sistema. Por esse motivo, novas metodologias e ferramentas computacionais usando programação estocástica são desenvolvidas para modelizar a variabilidade e incerteza inerente à geração eólica e solar. A convergência para uma solução ótima é garantida usando programação linear inteira-mista para formular o problema

Connecting office buildings to the smart grid:harvesting flexibility

Traditionally, the electricity system is oriented top- down and buildings are just energy consumers. Since electricity is expensive to store, supply and demand have to be balanced at all times. In the nearby future, the electricity system must be able to cope with an increase in intermittent decentralized energy production. Also, ongoing electrification is expected to contribute to an increase in demand. Demand side management and control is needed to ensure reliability of supply at acceptable costs. Buildings can be a part of the solution as they can offer flexibility in energy consumption and/or production. By enabling flexible control of processes on the building premises, the building can provide balancing services and respond to congestion problems in the power system, while user comfort can be guaranteed. For the engineering company BAM Techniek, it is of importance to know how the integration of such smart grid technologies in buildings can contribute to (energy) service provision. This study focusses on the enabling of flexibility in energy consumption and generation, while comfort is guaranteed. The project aims to create a framework that enables flexible control of building processes, and analyses of the potential value of flexibility in office buildings. The proposed framework consists of a technical solution, and an analysis of the economical benefits. Priority based control is introduced to enable flexible control of building processes. The concept is capable of prioritizing the energy consumption of processes, and controlling the consumption depending on the needs of the electricity market. An empty office has for instance, a low priority to consume energy. User needs are integrated in the prioritization mechanisms. This mechanism ensures that processes stay within the allowed bandwidth, while providing flexibility to the power system. Since the priority based control connects the end user needs to the market needs, a bi-directional flow of information is required. The Eneco World Office is used to perform a building case study to test the technological framework. Three sources of flexibility are investigated: decentralized climate systems, electric vehicles, and a sensible heat buffer. Results show that the amount of available flexibility depends mainly on load profiles and comfort settings. Electric vehicles and the sensible heat buffer provide significant amounts of flexibility. The flexibility in decentralized climate systems is limited since the room air temperature responds relatively fast to changes in settings and comfort boundaries are quickly met. The long term effect of storage in the building inertia should however be investigated further. Economical benefits can be created by using the variation in costs on the wholesale market caused by market volatility. When flexibility is used to contribute to the balance in a portfolio of buildings, the imbalance can be reduced, which leads to a reduction in costs. Finally, flexibility can contribute to a reduction in peak demand of buildings, leading to cost savings in the network connection. The need for smart grids is growing, while energy services are becoming more important in the built environment. Considering the potential value of smart grid services in the built environment and the market size, it is evident that the developing smart grid market presents opportunities for BAM Techniek. The provision of flexibility services can be a valuable addition to the energy services portfolio

A System Complexity Approach to Swarm Electrification

The study investigates a bottom-up concept for microgrids. Financial analysis is performed through a business model approach to test for viability when replacing a researched energy expenditure baseline in Bangladesh. A literature review compares the approach to current trends in microgrids. A case study of Bangladesh illustrates the potential for building on the existing infrastructure base of solar home systems. Opportunities are identified to improve access to reliable energy through a microgrid approach that aims at community-driven economic and infrastructure development by building on network effects generated through the inclusion of localized economies with strong producer-consumer linkages embedded within larger systems of trade and exchange. The analysed approach involves the linking together of individual stand-alone energy systems to form a microgrid that can eventually interconnect with present legacy infrastructure consisting of national or regional grids. The approach is likened to the concept of swarm intelligence, where each individual node brings independent input to create a conglomerate of value greater than the sum of its parts

Load Balancing in the Smart Grid: A Package Auction and Compact Bidding Language

Distribution system operators (DSOs) are faced with new challenges from the continuous integration of fluctuating renewable energy resources and new dynamic customer loads such as electric vehicles, into the power grid. To ensure continuous balancing of supply and demand, we propose procurement package auctions to allocate load flexibility from aggregators and customers. The contributions of this research are an incentive-compatible load flexibility auction along with a compact bidding language. It allows bidders to express minimum and maximum amounts of flexibility along with unit prices in single bids for varying time periods. We perform a simulation-based evaluation and assess costs and benefits for DSOs and balancing suppliers given scenarios of varying complexity as well as computational aspects of the auction. Our initial findings provide evidence that load flexibility auctions can reduce DSO costs substantially and that procurement package auctions are well-suited to address the grid load balancing problem

A survey on enhancing grid flexibility through bidirectional interactive electric vehicle operations

Smart grids (SG) constitute a revolutionary concept within the energy sector, enabling the establishment of a bidirectional communication infrastructure. This infrastructure significantly improves control, efficiency, and overall service quality in power systems. The study provides an in-depth survey on the classification of EVs, including both plug-in and non-plug-in EVs, and the integration process of V2G, including bidirectional power flow analysis. Moreover, various control strategies for EV integration are explored, ranging from centralized and decentralized to hierarchical control structures. Further, the research thoroughly examines the potential benefits of EV integration and addresses associated challenges, such as battery degradation, infrastructure requirements, cybersecurity and communication issues, grid congestion, and consumer behavior. The study goes beyond theoretical exploration and offers a comprehensive simulation analysis. This analysis leverages the storage capabilities of EVs to provide grid support services. A real-time dynamic dispatch strategy is formulated to integrate EVs into the automatic generation control of multi-energy systems. The findings demonstrate that EVs can effectively mitigate forecasting errors in a power network heavily reliant on wind energy sources. Consequently, the storage capabilities of EVs contribute to enhancing grid flexibility in managing the intermittency of renewable energy resources