Yes / The fast‐growing offshore wind energy sector brings opportunities to provide a sustainable energy resource but also challenges in offshore wind turbine (OWT) operation and maintenance management. Existing operational simulation models assume deterministic input reliability and failure cost data, whereas OWT reliability and failure costs vary depending on several factors, and it is often not possible to specify them with certainty. This paper focuses on modelling reliability and failure cost uncertainties and their impacts on OWT operational and economic performance. First, we present a probabilistic method for modelling reliability data uncertainty with a quantitative parameter estimation from available reliability data resources. Then, failure cost uncertainty is modelled using fuzzy logic that relates a component's failure cost to its capital cost and downtime. A time‐sequential Monte Carlo simulation is presented to simulate operational sequences of OWT components. This operation profile is later fed into a fuzzy cost assessment and coupled with a wind power curve model to evaluate OWT availability, energy production, operational expenditures and levelised cost of energy. A case study with different sets of reliability data is presented, and the results show that impacts of uncertainty on OWT performance are magnified in databases with low components' reliability. In addition, both reliability and cost uncertainties can contribute to more than 10% of the cost of energy variation. This research can provide practitioners with methods to handle data uncertainties in reliability and operational simulation of OWTs and help them to quantify the variability and dependence of wind power performance on data uncertainties. / Engineering and Physical Sciences Research Council. Grant Number: EP/P009743/1

Made available in DSpace on 2015-05-08T14:53:17Z (GMT). No. of bitstreams: 1 arquivototal.pdf: 3747541 bytes, checksum: 321b5f29863e2f68953902273ae4cb9f (MD5) Previous issue date: 2011-08-15 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / The main goal of this dissertation is to design and implementation of an Operational Simulation Model (OSM) of the handling of raw material in an Integrated Steelmaking Plant, considering operations of receiving, unloading, stocking, handling and supplying the different raw materials related to the production process with an operational perspective. The aim of this focus is to help in the decision making of the team controlling the ore inventory. The construction of this computer model was based on the methodological framework developed by Coelho, which passed through problem formulation, planning and elaboration of a detailed specification of the model. The OSM showed that most of the valid concepts for simulations with a strategic focus do not present relevance from an operational point of view. The advantage of the OSM is the fact that it is not random or stochastic, but deterministic. The methodology allowed the model elaboration with a minimum effort and great consistency. The results of scenarios with scheduled equipment stops have shown the simulator s flexibility, with previous identification of bottlenecks and allowed the decision making of corrective actions for avoid them on real situations. The filling of the stockyard map using results of consistent scenarios was a great advance in order to automate this activity. The correct behaviour of the simulator allowed the raw material yard team to consider the well succeeded study. / O objetivo principal desta dissertação é construir um modelo de simulação operacional do manuseio de matérias-primas de uma usina siderúrgica integrada, contemplando as operações de recebimento, descarga, estocagem, manuseio e abastecimento das diversas matérias-primas pertinentes ao processo produtivo, com foco operacional, visando auxiliar a tomada de decisões operacionais da equipe que controla o pátio. A construção desse modelo computacional se baseou na estrutura metodológica desenvolvida por Coelho, que passou pela formulação do problema, planejamento do estudo e pela elaboração de uma especificação detalhada do modelo. O modelo de simulação operacional revelou que grande parte dos conceitos válidos para simulações com foco estratégico não representa tanta relevância sob o ponto de vista operacional. Mas a vantagem do modelo de simulação operacional é a ausência de aleatoriedade, não é estocástico, mas sim determinístico. A metodologia inédita, utilizada para desenvolvimento do modelo do pátio de matérias-primas, permitiu a elaboração do modelo com o mínimo de retrabalho e com grande consistência. Os resultados dos cenários, com paradas programadas dos equipamentos, mostraram a flexibilidade do simulador, permitindo a identificação prévia de gargalos e possibilitando a tomada de ações corretivas para evitá-los nas situações reais. O preenchimento do mapa do pátio, a partir de resultados de cenários consistentes, foi um grande avanço, no sentido de automatizar esta atividade. O comportamento correto do simulador permitiu que a equipe do pátio de matérias-primas considerasse o estudo muito bem sucedido.