Dynamic Electric Dispatch for Wind Power Plants: A New Automatic Controller System Using Evolutionary Algorithms

In this paper, we use an evolutionary swarm intelligence approach to build an automatic electric dispatch controller for an offshore wind power plant (WPP). The optimal power flow (OPF) problem for this WPP is solved by the Canonical Differential Evolutionary Particle Swarm Optimization algorithm (C-DEEPSO). In this paper, C-DEEPSO works as a control system for reactive sources in energy production. The control operation takes place in a daily energy dispatch, scheduled into 15 min intervals and resulting in 96 operating test scenarios. As the nature of the optimization problem is dynamic, a fine-tuning of the initialization parameters of the optimization algorithm is performed at each dispatch interval. Therefore, a version of the C-DEEPSO algorithm has been built to automatically learn the best set of initialization parameters for each scenario. For this, we have coupled C-DEEPSO with the irace tool (an extension of the iterated F-race (I/F-Race)) by using inferential statistic techniques. The experiments carried out showed that the methodology employed here is robust and able to tackle this OPF-like modeling. Moreover, the methodology works as an automatic control system for a dynamic schedule operation

Improved methodologies for security of electricity supply of future power system

The security of electricity supply has always been important, but it has recently become one of the critical issues for the planning and operation of modern electricity networks. There are several reasons for that, including increased demands and deregulation of electricity markets, resulting in much lower infrastructural investments, which both pushed existing networks to operate closer to their security limits. The increasing penetration levels of variable and inherently non-dispatchable renewable energy resource, as well as the implementation of demand-responsive controls and technologies on the demand side, together with the application of real-time thermal ratings for system components, have introduced an unprecedented level of uncertainties into the system operation. These uncertainties present genuinely new challenges for the maintenance of high system security levels. The first contribution of this thesis is the development of advanced computational tools to strengthen the decision-making capabilities of system operators and ensure secure and economic operation under high uncertainty levels. It initially evaluates the hosting capacities for wind-based generation in a distribution network subject to operational security limits. In order to analyse the impacts of variations and uncertainties in the wind-based generation, loads and dynamic thermal ratings of network components, both deterministic and probabilistic approaches are applied for hosting capacity assessment at each bus, denoted as “locational hosting capacity”, which is of interest to distributed generation (DG) developers. Afterwards, the locational hosting capacities are used to determine the hosting capacity of the whole network, denoted as “network hosting capacity”, which is of primary interest to system operators. As the available hosting capacities change after the connection of any DG units, a sensitivity analysis is implemented to calculate the variations of the remaining hosting capacity for any number of DG units connected at arbitrary network buses. The second contribution of this thesis is a novel optimisation model for the active management of networks with a high amount of wind-based generation and utilisation of dynamic thermal ratings, which employs both probabilistic analysis and interval/affine arithmetic for a comprehensive evaluation of related uncertainties. Affine arithmetic is applied to deal with interval information, where the obtained interval solutions cover the full range of possible optimal solutions, with all realisations of uncertain variables. However, the interval solutions overlook the probabilistic characteristics of uncertainties, e.g. a likely very low probabilities around the edges of intervals. In order to consider realistic probability distribution information and to reduce overestimation errors, the affine arithmetic approach is combined with probabilistic (Monte Carlo) based analysis, to identify the suitable ranges of uncertainties for optimal balancing of risks and costs. Finally, this thesis proposes a general multi-stage framework for efficient management of post-contingency congestions and constraint violations. This part of the work uses developed thermal models of overhead lines and transformers to calculate the maximum lead time for system operators to resolve constraint violations caused by post-fault contingency events. The maximum lead time is integrated into the framework as the additional constraint, to support the selection of the most effective corrective actions. The framework has three stages, in which the optimal settings for volt-var controls, generation re-dispatch and load shedding are determined sequentially, considering their response times. The proposed framework is capable of mitigating severe constraint violations while preventing overheating and overloading conditions during the congestion management process. In addition, the proposed framework also considers the costs of congestion management actions so that the effective corrective actions can be selected and evaluated both technically and economically

Criação de um framework para ajuste fino de parâmetros usando testes estatísticos

Neste trabalho, foi criado um framework para realização do ajuste fino de parâmetros em uma meta-heurística evolutiva para problemas de eficiência energética. Foi realizado o ajuste fino no Canonical Differential Evolutionary Particle Swarm Optimization (C-DEEPSO), um algoritmo de otimização criado a partir da fusão de duas outras meta-heurísticas, o Differential Evolution (DE) e o Evolutionary Particle Swarm Optimization (EPSO). Esse ajuste fino foi efetuado pelo método de corrida iterativa com ajuda de um pacote chamado iRace. Neste método, são realizadas várias simulações do algoritmo com diferentes parâmetros e são identificadas as melhores configurações possíveis com a aplicação de testes de hipóteses. Em um primeiro momento, o framework foi testado em duas funções de benchmark, as funções de Rastrigin e Rosenbrock para 30, 50 e 100 dimensões. Uma vez validada a eficácia do framework, o mesmo foi aplicado a um problema de eficiência energética de uma usina eólica offshore, com foco na redução da perda de energia. Este problema de eficiência energética possui natureza dinâmica, sendo composto por 96 instâncias, que caracterizam a discretização de 24 horas divididas entre intervalos de 15 minutos. A partir dos resultados obtidos via framework, uma comparação com o método estado da arte, o Mean-Variance Mapping Optimization (MVMO) foi realizada com uso da ferramenta DSCTool. Os resultados mostraram que o algoritmo C-DEEPSO com seus principais parâmetros ajustados obtém em média resultados otimizados mais robustos que os apresentados pelo MVMO. É evidenciado que a aplicação do C-DEEPSO com parâmetros tunados no lugar do MVMO resultaria em uma redução de perdas de 70.02MWh, energia suficiente para abastecimento de cerca de 450 residências

Regulación de frecuencia en sistemas de potencia que integran fuentes de energía renovables, mediante un controlador PI e imitación inercial

En este trabajo final de maestría, se presenta el estudio y análisis de un esquema de control de regulación de frecuencia en un sistema de potencia (IEEE 14 bus test system) que integra fuentes de energía renovable (RES), para mejorar la confiabilidad y estabilidad de la red. Inicialmente, se simuló la respuesta dinámica del sistema de potencia ante distintas perturbaciones (escalón, triangular y compuesta), a fin de obtener las desviaciones de frecuencia en el nodo de referencia. Así mismo, se implementó un bloque de control en el lazo de potencia adicional para emular la “imitación inercial” y de esta manera ralentizar y corregir la respuesta del sistema. Posteriormente, se procedió a optimizar los parámetros de control, a través de algoritmos heurísticos con el objetivo de minimizar el error de la señal de frecuencia. Finalmente, se presentan los resultados más destacados del estudio, para proyectar un trabajo futuro en el ámbito del despacho económico, considerando la estabilidad del sistema.Abstract. In this final master's work, the study and analysis of a control scheme of frequency regulation in a power system (IEEE 14 bus test system) integrating renewable energy sources (RES) is presented, to improve the reliability and stability of the network. Initially, the dynamic response of the power system to different perturbations (step, triangular and composite) was simulated in order to obtain the frequency deviations in the reference node. Also, a control block was implemented in the additional power loop to emulate the "inertial imitation" and in this way to slow down and correct the system response. Subsequently, we optimized the control parameters, through heuristic algorithms with the objective of minimizing the error of the frequency signal. Finally, the most outstanding results of the study are presented, for project future work in the field of economic dispatch, considering the stability of the system.Maestrí

Battery storage systems as balancing option in intermittent renewable energy systems - A transdisciplinary approach under the frame of Constructive Technology Assessment

Different battery storage technologies are considered as important flexibility option in the face of increasing shares of renewables in the grid. A challenge is to support decision-making by providing a broader perspective on battery technology development, choice, and implementation. The tailored approach in the frame of Constructive Technology Assessment (CTA) in combination with system analysis allows it to explore actor visions and expectations about battery storage and to use this information to provide quantitative information about the consequences of these. Research results combine the perspectives of technology and non-technology related actors (enactors and selectors) to create new and broader knowledge to provide “better” technology. Major implications identified for battery storage are missing business models, uncertain regulations, and doubts about their techno-economic viability. A highlight is a proof that expectations about technology characteristics in orientation to sustainability criteria are settled within concentric perspectives by using the Analytic-Hierarchy-Process (AHP). Enactors focus on economic and technological criteria which reflect the concentric bias of this group. In contrast, selectors perceive environmental and social criteria as more important. The consensus among actors regarding criteria importance is not existent to moderate which indicates that more research is required here. System analysis is used to quantify actor preferences obtained through the AHP. Li-Ion-batteries (LIB), lead-acid-batteries (VRLA), high-temperature-batteries (NaNiCl and NaS), and Vanadium-redox-flowbatteries (VRFB) are evaluated through e.g. life cycle assessment and costing for four different application fields (decentralized storage, wind energy support, primary regulation and energy-time-shift (ETS-includes compressed-air-energy-storage (CAES) and pumped-hydro-storage (PHS)). Preliminary rankings indicate that most LIBs can be recommended for all application areas, wherein decentralized storage is considered to offer the highest potentials for battery storage. VRLA and NaS achieve rather low scores whereas ranking of VRFB is highly dependent on the considered use case. PHS and CAES dominate all assessed energy storage technologies in the ETS application case

1. Helgoland Power and Energy Conference - 24. Dresdener Kreis 2023

Der Sammelband "1. Helgoland Power and Energy Conference" beinhaltet neben einem kurzen Bericht zum 24. Treffen des Dresdener Kreises 2023 wissenschaftliche Beiträge von Doktoranden der beteiligten Hochschulinstitute zum Thema Elektroenergieversorgung. Der Dresdener Kreis setzt sich aus der Professur für Elektroenergieversorgung der Technischen Universität Dresden, dem Fachgebiet Elektrische Anlagen und Netze der Universität Duisburg-Essen, dem Fachgebiet Elektrische Energieversorgung der Leibniz Universität Hannover und dem Lehrstuhl Elektrische Netze und Erneuerbare Energie der Otto-von-Guericke Universität Magdeburg zusammen und trifft sich einmal im Jahr zum fachlichen Austausch an einer der beteiligten Universitäten

Políticas de Copyright de Publicações Científicas em Repositórios Institucionais: O Caso do INESC TEC

A progressiva transformação das práticas científicas, impulsionada pelo desenvolvimento das novas Tecnologias de Informação e Comunicação (TIC), têm possibilitado aumentar o acesso à informação, caminhando gradualmente para uma abertura do ciclo de pesquisa. Isto permitirá resolver a longo prazo uma adversidade que se tem colocado aos investigadores, que passa pela existência de barreiras que limitam as condições de acesso, sejam estas geográficas ou financeiras. Apesar da produção científica ser dominada, maioritariamente, por grandes editoras comerciais, estando sujeita às regras por estas impostas, o Movimento do Acesso Aberto cuja primeira declaração pública, a Declaração de Budapeste (BOAI), é de 2002, vem propor alterações significativas que beneficiam os autores e os leitores. Este Movimento vem a ganhar importância em Portugal desde 2003, com a constituição do primeiro repositório institucional a nível nacional. Os repositórios institucionais surgiram como uma ferramenta de divulgação da produção científica de uma instituição, com o intuito de permitir abrir aos resultados da investigação, quer antes da publicação e do próprio processo de arbitragem (preprint), quer depois (postprint), e, consequentemente, aumentar a visibilidade do trabalho desenvolvido por um investigador e a respetiva instituição. O estudo apresentado, que passou por uma análise das políticas de copyright das publicações científicas mais relevantes do INESC TEC, permitiu não só perceber que as editoras adotam cada vez mais políticas que possibilitam o auto-arquivo das publicações em repositórios institucionais, como também que existe todo um trabalho de sensibilização a percorrer, não só para os investigadores, como para a instituição e toda a sociedade. A produção de um conjunto de recomendações, que passam pela implementação de uma política institucional que incentive o auto-arquivo das publicações desenvolvidas no âmbito institucional no repositório, serve como mote para uma maior valorização da produção científica do INESC TEC.The progressive transformation of scientific practices, driven by the development of new Information and Communication Technologies (ICT), which made it possible to increase access to information, gradually moving towards an opening of the research cycle. This opening makes it possible to resolve, in the long term, the adversity that has been placed on researchers, which involves the existence of barriers that limit access conditions, whether geographical or financial. Although large commercial publishers predominantly dominate scientific production and subject it to the rules imposed by them, the Open Access movement whose first public declaration, the Budapest Declaration (BOAI), was in 2002, proposes significant changes that benefit the authors and the readers. This Movement has gained importance in Portugal since 2003, with the constitution of the first institutional repository at the national level. Institutional repositories have emerged as a tool for disseminating the scientific production of an institution to open the results of the research, both before publication and the preprint process and postprint, increase the visibility of work done by an investigator and his or her institution. The present study, which underwent an analysis of the copyright policies of INESC TEC most relevant scientific publications, allowed not only to realize that publishers are increasingly adopting policies that make it possible to self-archive publications in institutional repositories, all the work of raising awareness, not only for researchers but also for the institution and the whole society. The production of a set of recommendations, which go through the implementation of an institutional policy that encourages the self-archiving of the publications developed in the institutional scope in the repository, serves as a motto for a greater appreciation of the scientific production of INESC TEC