Thesis (Ph. D.)--Division of Geography, School of Geosciences, Faculty of Science, University of Sydney, 2006. / Title from title screen (viewed 15 January 2009). Submitted in fulfilment of the requirements for the degree of Doctor of Philosophy to the School of Geosciences, Faculty of Science. Includes bibliographical references. Also available in print form.

Orientador: Leonardo Nepomuceno / Banca: Marcelo Augusto Cicogna / Banca: Edmea Cassia Baptista / Resumo: No ambiente regulado, o planejamento da geração de energia é coordenado por um operador do sistema, que procura minimizar os custos da energia gerada e garantir a segurança energética para os consumidores e o atendimento da demanda. Este tipo de planejamento de geração não representa a lei de oferta e procura que ocorre em mercados de energia elétrica. No ambiente de mercado, os agentes apresentam suas ofertas de compra e venda em um ambiente competitivo que promove a livre concorrência. Este trabalho propõe um modelo de planejamento de geração de médio prazo, baseado na concorrência pela geração/consumo, em que empresas geradoras e consumidores fornecem lances em um leilão de energia de médio prazo. O modelo proposto é comparado ao modelo de planejamento centralizado de geração de energia. Os testes realizados no software GAMS, com pacote de solução CPLEX, indicam que o modelo proposto é uma alternativa para promover uma matriz energética mais variada e robusta a variações climáticas, além de manter a concorrência justa tanto para os consumidores quanto para os produtores de energia. / Abstract: In regulated hydrothermal electricity markets, power generation dispatch is coordinated by an independent system operator, that works to guarantee energy for consumers in the long-term, to meet the demand and to minimize the cost of generation. This type of dispatch does not represents the laws of supply and demand in the electricity market. In the deregulated auction market, the participants present their bids to purchase and sell, without the guarantee of being accepted, promoting free competition. This work presents a bibliographical research on electricity markets and the existing uncertainties of energy planning. Through optimization models, regulated dispatch is compared to an auction model for medium-term planning horizons. The tests performed in the GAMS software, with CPLEX solution package, indicate that the energy auction model is an alternative to promote the variation of the energy matrix, to turn it more robust to climate changes, in addition to maintaining fair competition for both the consumer and the producer. / Mestre

Battery charging wind turbines like, Hybrid Field Generator, have become more popular in the growing renewable energy market. With wind energy, voltage and current control is generally provided by means of power electronics. The paper describes the analytical investigation in to control aspects of a hybrid field generator controller for optimized performance. The project objective is about maintaining the generated voltage at 28V through out a generator speed range, between 149 rpm and 598 rpm. The over voltage load, known as dump load, is connected to the control circuit to reduce stress on the bypass transistor for speeds above 598 rpm. Maintaining a stable voltage through out the speed range, between 149rpm and 598rpm, is achieved by employing power electronics techniques. This is done by using power converters and inverters to vary the generator armature excitation levels hence varying its air gap flux density. All these take place during each of the three modes of generator operation, which are: buck, boost and permanent magnet modes. Although the generator controller is power electronics based, it also uses software to optimize its performance. In this case, a PIC16F877 microcontroller development system has been used to test the controller function blocks.

The threat of climate change has led to many countries and regions adopting renewable targets. Scotland's is one of the most ambitious, with an aim to generate the equivalent to 100% of its electricity needs from renewable sources by 2020. Scotland has a very large renewable resource, primarily consisting of offshore and onshore wind, tidal stream, wave and hydro power; all of which are characterised by having variable output. Over a long period, such as a year, variability in renewable generation will average out and may meet or exceed total annual demand. This thesis investigates whether matching of demand and generation is possible within a timescale meaningful to electricity system users; that is whether renewable generation can meet electricity demand in any given hour. This was established by using historic data to create an hourly generation hindcast of Scotland's renewable generation over a 30 year climate “normal” period. These outputs are then compared to a hindcast of hourly demand based on observations over the most recent few years. The results demonstrated that it is possible for Scotland to rely entirely upon renewable generation to fulfil demand in any hour of the 30 year hindcast. However, it appears that the renewable capacity and storage currently built or within the Scottish planning system is only sufficient to match demand in 65% of the hours within the hindcast. The hindcast allows judgements to be made as to how 100% of demand could be met most effectively and provides the basis of a coherent planning strategy, with security of supply at its centre. Further wave and tidal stream capacity is shown to be of higher value than additional wind power but in the latter case, addressing the geographical diversity of wind power can enable maximise phasing between sites to increase the security of supply. Importantly this work provides a means of informing decision making about where best to develop wind, wave and tidal resources and what additional storage may be required in order to provide 100% security of supply. The results are also of particular importance to Scotland's renewable generation strategy in the case of assessing where new on- and off-shore wind farms should be developed, as wind is set to dominate Scotland's renewable portfolio for the foreseeable future.

The research described in this dissertation was motivated by the global demand for energy that is not dependent on coal, oil, natural gas and other non-renewable fossil fuels. The technology used in this project is related to the use of biomass to produce a viable alternative to conventional sources of fuel. A bench scale biomass to liquid (BTL) facility was built and tested. This produced results confirming the feasibility of the BTL process. The findings of the pilot study outlined in this dissertation justified the conclusion that the next step will be to expand the capacity and productivity of the BTL pilot plant to an industrial scale. Biomass comes from a variety of renewable sources that are readily available. In this case, the material used in the fixed bed biomass gasification facility to generate wood gas was agricultural and forestry waste, such as straw and wood chips. The gasifier had the capacity to produce up to 10 cubic metres/hr of gas with a carbon monoxide and hydrogen content of between 20–40% by volume, when it was operated at ambient pressure and with air as the oxidizer. The gas, produced at a temperature above 700º C, was cooled in a quench/water scrubber in order to remove most of the mechanical impurities (tars and water-soluble inorganic particles), condensed and dried with corn cobs before being compressed in cylinders at over 100 bar (g) for use in the Fischer-Tropsch Synthesis (FTS). The syngas was subjected further to a series of refining processes which included removal of sulphur and oxygen. The sulphur removal technology chosen entailed applying modified activated carbon to adsorb H2S with the help of hydrolysis in order to convert organic sulphur impurities into H2S which reduced the sulphur content of the gas to less than 5 ppbv. Supported cobalt catalyst (100 grams), were loaded into a single-tube fixed bed FT reactor with an inner diameter of 50 mm. The reactor was fitted with a heating jacket through which, heated oil ran to cool the reactor during a normal reaction occurring at < 250 ºC, while nitrogen was used in the heating jacket during reduction, which occurred at temperatures up ~ 350 ºC. The FTS reaction was carried out at different pressures and temperatures. Liquid and wax products were produced from the facility. The properties of the liquid and solid hydrocarbons produced were found to be the same as FT products from other feed stocks, such as natural gas and coal.

Thesis (Ph. D.)--University of Canterbury, 2006. / Typescript (photocopy). Includes bibliographical references (p. 459-469). Also available via the World Wide Web.

The use of electricity in 21st century living has been firmly established throughout most of the world, correspondingly the infrastructure for production and delivery of electricity to consumers has matured and stabilised. However, due to recent technical and environmental–political developments, the electricity infrastructure worldwide is undergoing major restructuring. The forces driving this reorganisation are a complex interplay of technical, environmental, economic and political factors. The general trend of the reorganisation is a dis–aggregation of the previously integrated functions of generation, transmission and distribution, together with the establishment of competitive markets, primarily in generation, to replace previous regulated monopolistic utilities. To ensure reliable and cost effective electricity supply to consumers it is necessary to have an accurate picture of the expected generation in terms of the spatial and temporal distribution of prices and volumes. Previously this information was obtained by the regulated utility using technical studies such as centrally planned unit–commitment and economic–dispatch. However, in the new deregulated market environment such studies have diminished applicability and limited accuracy since generation assets are generally autonomous and subject to market forces. With generation outcomes governed by market mechanisms, to have an accurate picture of expected generation in the new electricity supply industry, it is necessary to complement traditional studies with new studies of market equilibrium and stability. Models and solution methods have been developed and refined for many markets, however they cannot be directly applied to the generation market due to the unique nature of electricity, having high inelastic demand, low storage capability and distinct transportation requirements. Intensive effort is underway to formulate solutions and models that specifically reflect the unique characteristics of the generation market. Various models have been proposed including game theory, stochastic and agent–based systems. Similarly there is a diverse range of solution methods including, Monte–Carlo simulations, linear–complimentary and quadratic programming. These approaches have varying degrees of generality, robustness and accuracy, some being better in certain aspects but weaker in others. This thesis formulates a new general model for the generation market based on the Cournot game, it makes no conjectures about producers’ behaviour and assumes that all electricity produced is immediately consumed. The new formulation characterises producers purely by their cost curves, which is only required to be piece–wise differentiable, and allows consumers’ characteristics to remain unspecified. The formulation can determine dynamic equilibrium and multiple equilibria of markets with single and multiple consumers and producers. Additionally stability concepts for the new market equilibrium is also developed to provide discrimination for dynamic equilibrium and to enable the structural stability of the market to be assessed. Solutions of the new formulation are evaluated by the use of evolutionary computation, which is a guided stochastic search paradigm that mimics the operation of biological evolution to iteratively produce a population of solutions. Evolutionary computation is employed as it is adept at finding multiple solutions for underconstrained systems, such as that of the new market formulation. Various enhancements to significantly improve the performance of the algorithms and simplify its application are developed. The concept of convergence potential of a population is introduced together with a system for the controlled extraction of such potential to accelerate the algorithm’s convergence and improve its accuracy and robustness. A new constraint handling technique for linear constraints that preserves the solution’s diversity is also presented together with a coevolutionary solution method for the multiple consumers and producers market. To illustrate the new electricity market formulation and its evolutionary computation solution methods, the equilibrium and stability of a test market with one consumer and thirteen thermal generators with valve point losses is examined. The case of a multiple consumer market is not simulated, though the formulation and solution methods for this case is included. The market solutions obtained not only confirms previous findings thus validating the new approach, but also includes new results yet to be verified by future studies. Techniques for market designers, regulators and other system planners in utilising the new market solutions are also given. In summary, the market formulation and solution method developed shows great promise in determining expected generation in a deregulated environment.

Thesis (MBA)--Stellenbosch University, 2015. / ENGLISH ABSTRACT: Eskom, the South Africa and trans-Africa electrical power utility, has a capacity expansion project that is estimated to cost roughly R340 billion. The programme is anticipated to continue through 2018. Eskom will be contracting with a multitude of suppliers and it is imperative that the projects delivered under the capacity expansion programme meet Eskom’s required quality standards. The question then arises whether the set quality standards are sufficiently comprehensive to provide confidence that suppliers will achieve high quality standards. This aim of this research was to examine supplier assessment programmes to determine the criteria that will best provide supplier assurance. The researcher consulted a vast range of literature available on supplier quality assessment programmes. From the literature consulted, there appeared to be some recurring themes from the range of assessment tools. It also becomes apparent that the assessment tool cannot only focus on a quality system, but a balance of strategic and operational focus was needed to fully understand suppliers’ ability to deliver. One of the key considerations was establishing longer-term collaborative relationships with key suppliers. Long-term relations encourage trust, transparency and innovation. It was equally important to ensure that operational assessments provided insight on suppliers’ capability. Based on the literature reviewed, a proposed framework was tested against the current methodology for supplier evaluation. From these comparisons, some gaps were identified and recommendations were suggested to improve the supplier evaluation programme.

published_or_final_version / abstract / Electrical and Electronic Engineering / Master / Master of Philosophy

Tu, Jinlong. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2013. / Includes bibliographical references (leaves 92-95). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstracts also in Chinese.