abstract: Electric power system security assessment is one of the most important requirements for operational and resource planning of the bulk power system ensuring safe operation of the power system for all credible contingencies. This deterministic approach usually provides a conservative criterion and can result in expensive bulk system expansion plans or conservative operating limits. Furthermore, with increased penetration of converter-based renewable generation in the electric grid, the dynamics of the grid are changing. In addition, the variability and intermittency associated with the renewable energy sources introduce uncertainty in the electricity grid. Since security margins have direct economic impact on the utilities; more clarity is required regarding the basis on which security decisions are made. The main objective of this work is to provide an approach for risk-based security assessment (RBSA) to define dynamic reliability standards in future electricity grids. RBSA provides a measure of the security of the power system that combines both the likelihood and the consequence of an event. A novel approach to estimate the impact of transient stability is presented by modeling several important protection systems within the transient stability analysis. A robust operational metric to quantify the impact of transient instability event is proposed that incorporates the effort required to stabilize any transiently unstable event. The effect of converter-interfaced renewable energy injection on system reliability is investigated us-ing RBSA. A robust RBSA diagnostics tool is developed which provides an interactive user interface where the RBSA results and contingency ranking reports can be explored and compared based on specific user inputs without executing time domain simulations or risk calculations, hence providing a fast and robust approach for handling large time domain simulation and risk assessment data. The results show that RBSA can be used effectively in system planning to select security limits. Comparison of RBSA with deterministic methods show that RBSA not only provides less conservative results, it also illustrates the bases on which such security decisions are made. RBSA helps in identifying critical aspects of system reliability that is not possible using the deterministic reliability techniques. / Dissertation/Thesis / Doctoral Dissertation Electrical Engineering 2017

This thesis investigates the performance of business model innovation (BMI) by incumbent power utility and clean-tech start-up firms influenced by the German Energiewende. It emphasises the factors that impact BMI from a managers’ perspective, examines success factors for managers to overcome BMI challenges, and addresses contingencies to perform BMI in a more structured way. The research is driven by the German Energiewende. It has been chosen as Germany is considered one of the world’s leading markets for renewable energies and a transformation of the power sector is currently underway. Therefore, established power utility firms face severe changes, which have the characteristics of a potential disruption to their business model (BM). At the same time, new players are challenging these incumbents with new BMs. The research is underpinned by the extant literature on BMs and BMI. The research approach is based on two case studies; the incumbent power utility and the clean-tech start-up sector. The qualitative study comprises of 24 semi-structured interviews conducted with top tier managers, from 18 firms, responsible for BMI within these firms. Key findings: This study extends our knowledge of BMI in both a start-up and an incumbent environment that is influenced by various contingent events. It portrays barriers to BMI and depicts critical success factors for BMI that point out solutions on how to overcome these barriers. It provides a structured BMI framework for established firms and illustrates future BM archetypes in this sector. It clearly documents the German Energiewende is regarded as a disruptive threat from the perspective of incumbent power utility managers. The theoretical contribution of this thesis is a process framework including all identified drivers and challenges for BMI in both established and start-up firms. Contributions to practice include critical success factors for BMI, recommendations to overcome barriers to BMI and future BM archetypes within the newly evolving Energiewende industry based on sustainable technologies.

Since the late 1980s, the energy sector in Great Britain has undergone some core changes in its functionality; beginning with the early 1990s privatisation, followed by an increased green ambition, and commencing a transition towards a low-carbon economy. As the British energy sector prepares itself for another major overhaul, it also puts itself at risk for not being sufficiently prepared for the consequences this transition will have on the existing generating capacity, security of supply, and the national electricity market. Upon meeting existing targets, the government of the United Kingdom risks becoming complacent, putting energy regulation to the backseat and focusing on other regulatory tasks, while introducing cuts for thriving renewable and other low-carbon energy generating technologies. The government has implemented a variety of directives, initiatives, and policies that have sometimes been criticised due to their lack of clarity and potential overlap between energy and climate change directives. The government has introduced policies that aim to provide stable short-term solutions. However, a concrete way of resolving the energy trilemma and some of the long-term objectives and more importantly ways of achieving them are yet to be developed. This work builds on analysing each low-carbon technology individually by assessing its past and current state in the British energy mix. By accounting for the changes and progress the technology underwent in its journey towards becoming a part of the energy capacity in Great Britain, its impact on the future wholesale electricity prices is studied. Research covered in this thesis presents an assessment of the existing and incoming low-carbon technologies in Great Britain and their individual and combined impact on the future of British energy economics by studying their implications for the electricity market. The methodological framework presented here uses a cost-minimisation merit order model to provide useful insights for novel methods of electricity production and conventional thermal energy generation to aid with the aftermath of potential inadequate operational and fiscal flexibility. The thesis covers a variety of scenarios differing in renewable and thermal penetration and examines the impact of interconnection, energy storage, and demand side management on the British wholesale electricity prices. The implications of increasing low-carbon capacity in the British energy mix are examined and compared to similar developments across Europe. The analysis highlights that if the optimistic scenarios in terms of green energy installation are followed, there is sufficient energy supply, which results in renewable resources helping to keep the wholesale price of electricity down. However, if the desired capacity targets are not met, the lack of available supply could result in wholesale prices going up, especially in the case of a natural gas price increase. Although initially costly, the modernisation of the British grid leads to a long-term decrease in wholesale electricity prices and provides a greater degree of security of supply and flexibility for all market participants.

La solution pour l'énergie génératrice issue de sources non polluantes configure un problème mondial, indéterminé, complexe et progressif. Et certainement, passe par la diversification de la matrice énergétique. La diversification signifie non seulement que des sources différentes sont converties en énergie utile, comme l'électricité, mais aussi décentraliser la production d'énergie afin de s'adapter à une plus grande adéquation de la demande, qui est décentralisée aussi. La Génération Distribuée propose ce type de développement, mais pour accroître sa pénétration, plusieurs obstacles techniques doivent être surpassés. L'un d'entre eux est lié aux systèmes de conversion, qui doivent être plus flexibles, modulaires, efficaces et compatibles avec les différentes sources d'énergie, car ils sont très spécifiques pour une certaine zone. La présente étude pousse ses efforts vers cette direction, c'est-à-dire comportant un système avec plusieurs entrées pour combiner différentes sources d'énergie renouvelables en un seul et efficace convertisseur de puissance pour la connexion au réseau. Elle porte sur la conception et le contrôle d'un système de production hybride de 11,7 kW utilisant des panneaux solaires photovoltaïques et une éolienne. Un convertisseur multicellulaire divisé en deux parties réalise la conversion: Convertisseur Côté Génération (GSC) et Convertisseur Côté Réseau (MSC). Les deux convertisseurs élévateurs (boost) responsables de la conversion photovoltaïque et du redresseur et de boost du générateur éolien, ainsi que les inductances d'entrée et les condensateurs, effectuent le GSC. La GSC permet la conversion en une tension de liaison CC fixe, mais garantit également la commande indépendante pour chaque entrée permettant le suivi du point de puissance maximum des panneaux et de l'éolienne. De l'autre côté, le MSC monophasé a quatre cellules effectue la connexion au réseau à travers un filtre LCL. Ce filtre utilise un Intercell Transformers (ICT) ou inducteurs couplés magnétiquement dans la première inductance pour réduire l'ondulation individuelle actuelle générée par la commutation. Le MSC contrôle la tension de la liaison CC et, ce faisant, il permet le flux de puissance des éléments de génération vers le réseau. / The solution for the generating energy derived from non-polluting sources configures a worldwide problem, which is undetermined, complex, and gradual; and certainly, passes through the diversification of the energetic matrix. Diversification means not only having different sources converted into useful energy, like the electricity, but also decentralizing the energy generation in order to fit with higher adequacy the demand, which is decentralized too. Distributed Generation proposes this sort of development but in order to increase its penetration several technical barriers must be overpassed. One of them is related to the conversion systems, which must be more flexible, modular, efficient and compatible with the different energy sources, since they are very specific for a certain area. The present study drives its efforts towards this direction, i.e. having a system with several inputs for combining different renewable energy sources into a single and efficient power converter for the grid connection. It focuses on the design and control of an 11.7 kW hybrid renewable generation system, which contains two parallel circuits of photovoltaic panels and a wind turbine. A multicell converter divided in two stages accomplishes the convertion: Generation Side Converter (GSC) and Mains Side Converter (MSC). Two boost converters responsible for the photovoltaic generation and a rectifier and a third boost, for the wind constitue the GSC. It allows the conversion to the fixed output DC voltage, controlling individually and performing the maximum power point tracking in each input. On the other side, the single-phase 4- cell MSC accomplishes the connection to the grid through an LCL filter. This filter uses an Intercell Transformer (ICT) in the first inductor for reducing the individual ripple generated by the swicthing. The MSC controls the DC-link voltage and, by doing that, it allows the power flow from the generation elements to the network.

This thesis investigates the performance of business model innovation (BMI) by incumbent power utility and clean-tech start-up firms influenced by the German Energiewende. It emphasises the factors that impact BMI from a managers’ perspective, examines success factors for managers to overcome BMI challenges, and addresses contingencies to perform BMI in a more structured way. The research is driven by the German Energiewende. It has been chosen as Germany is considered one of the world’s leading markets for renewable energies and a transformation of the power sector is currently underway. Therefore, established power utility firms face severe changes, which have the characteristics of a potential disruption to their business model (BM). At the same time, new players are challenging these incumbents with new BMs. The research is underpinned by the extant literature on BMs and BMI. The research approach is based on two case studies; the incumbent power utility and the clean-tech start-up sector. The qualitative study comprises of 24 semi-structured interviews conducted with top tier managers, from 18 firms, responsible for BMI within these firms. Key findings: This study extends our knowledge of BMI in both a start-up and an incumbent environment that is influenced by various contingent events. It portrays barriers to BMI and depicts critical success factors for BMI that point out solutions on how to overcome these barriers. It provides a structured BMI framework for established firms and illustrates future BM archetypes in this sector. It clearly documents the German Energiewende is regarded as a disruptive threat from the perspective of incumbent power utility managers. The theoretical contribution of this thesis is a process framework including all identified drivers and challenges for BMI in both established and start-up firms. Contributions to practice include critical success factors for BMI, recommendations to overcome barriers to BMI and future BM archetypes within the newly evolving Energiewende industry based on sustainable technologies.

[pt] A sazonalidade das fontes de geração de energia impacta as etapas de operação e planejamento do setor elétrico, pois provocam, dentre outros, variações de perfil de geração ao longo do ano. Diferentes tipos de usinas, como as hidráulicas, eólicas e térmicas à biomassa, têm sua disponibilidade afetada por causa do regime de chuvas, da intensidade dos ventos ou dos períodos de safra, respectivamente. Nessa dissertação, conduz-se um estudo sobre o impacto da sazonalidade hídrica na precisão de equivalentes de redes, por meio de fluxo de potência probabilístico via simulação Monte Carlo. As redes reduzidas são amplamente empregadas em estudos de planejamento da operação e da expansão do sistema elétrico. Uma das vantagens em sua adoção é a possibilidade de realizar um elevado número de simulações, com menor exigência computacional. A precisão dos equivalentes, nessa dissertação, é quantificada, considerando incertezas na demanda, variação de perfil de geração e a ocorrência de contingências de elementos de transmissão. São avaliados três métodos de redução de redes, em dois ambientes de simulação: cronológico e não cronológico. O primeiro tem o objetivo de analisar o impacto da utilização de um equivalente, obtido a partir da configuração típica de um mês especifico, nos demais meses do ano. O segundo visa comparar as diferentes metodologias de redução de rede diante de variações no ponto de redução, como contingências na transmissão. Os estudos são realizados com os sistemas IEEE 24 barras e IEEE 118 barras. Os equivalentes são elaborados com o software Organon e avaliados em MATLAB. Os resultados das simulações são amplamente discutidos e ressalta-se a importância do uso da rede reduzida adequada para garantia de resultados coerentes. / [en] The seasonality of energy generation sources impacts the operation and planning stages of the electricity sector, as they cause variations in the generation profile throughout the year. Different types of plants, such as hydraulic, wind, and biomass thermal plants, have their availability impacted due to the rainfall regime, the intensity of the winds, or the harvest periods, respectively. In this dissertation, a study is conducted on the impact of hydrological seasonality on the accuracy of network equivalents through probabilistic power flow via Monte Carlo simulation. Reduced networks are widely used in planning studies to operate and expand the electrical system. One of the advantages of its adoption is the possibility of performing a high number of simulations with less computational demand. The precision of the equivalents in this dissertation is quantified, considering the uncertainties in demand, variation of the generation profile, and the occurrence of contingencies of transmission elements. Three network reduction methods are considered in two simulation environments: chronological and non-chronological. The first is to analyze the impact of using an equivalent obtained from the typical configuration of a specific month in the other months of the year. The second aims to compare the different network reduction methodologies in the face of variations in the reduction point, such as transmission contingencies. The studies are carried out with the IEEE 24 bus and IEEE 118 bus systems. The equivalents are created with the Organon software and evaluated in MATLAB. The simulation results are widely discussed, highlighting the importance of using the reduced network to guarantee consistent results.

[pt] A complementaridade entre os perfis de geração renovável tem sido amplamente explorada na literatura. No entanto, as estruturas regulatórias eeconômicas para usinas híbridas de energia apresentam desafios e oportunidades interessantes para investidores, reguladores e planejadores. Focando nomercado de energia brasileiro, este artigo propõe um cálculo unificado e isonômico de Garantia Física (GF) para geradores renováveis não controláveis, quenos permite 1) generalizar o conceito de GF para unidades híbridas e 2) capturar as sinergias regulatórias e econômicas entre as fontes. Com base na GFnão discriminatória proposta para usinas híbridas de energia, a co-otimizaçãodas estratégias de contratação de energia no mercado de futuro e da rede, o Montante de Uso do Sistema de Transmissão (MUST), é estudada, e seus incentivos econômicos são demonstrados. A participação ótima de fontes renováveisque compõem a geração da usina híbrida também é considerada no modelo eanalisada em nossos estudos de caso. Com base em dados reais do mercadode energia brasileiro, quantificamos os benefícios das estruturas e modelos demercado propostos para uma unidade híbrida típica de eólico-solar. / [en] The complementarity between renewable generation profiles has been widely explored in literature. Notwithstanding, the regulatory and economic frameworks for hybrid power plants add interesting challenges and opportunities for investors, regulators, and planners. Focusing on the Brazilian power market, this paper proposes a unified and isonomic firm energy certificate (FEC) calculation for non-controllable renewable generators, which allows us to 1) generalize the FEC concept for hybrid units and 2) capture the regulatory and economic synergies between sources. Based on the non-discriminatory FEC proposed for hybrid power plants, the co-optimization of both forward-market and network-access contracting strategies is studied, and its economic incentives are demonstrated. The optimal share of renewable sources composing the hybrid power plant is also considered in the model and analyzed in our case studies. Based on real data from the Brazilian power market, we quantify the benefits of the proposed market structures and model for a typical wind–solar hybrid unit.