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M.Tech. / In life extending and refurbishing old power station plant, the following question must be addressed: Does one maintain current configuration, which was based on the technology of 1960, or make use of current power utility technology trends, and change the power station's configuration. This specific problem involves four existing Eskom power stations, with an approximate combined replacement value of R7 billion. All these stations have the capability of using a common steam feed range to supply superheated steam to the turbo-generator sets. This common steam feed range becomes very maintenance intensive in its "old age". Hence the need for this study into the feasibility of its refurbishment. This common steam feed range configuration was considered state-of-the-art in the mid-1900's, but is currently not the practised technology. This is primarily due to the technology advancement into reheat boilers, making control of a range type configuration impossible. Monte Carlo simulation provides an effective, holistic decision mechanism, that is free from bias, emotions and conjecture. Hence the simulation product, highlighted in this dissertation, will have solved an industrial problem finally and effectively, by ensuring that for a relatively small cost of building the simulation models, major capital expenditure estimates can be accurate, with a confidence in the return on investment. This paper discusses the use of Monte Carlo simulation modelling as an engineering analysis tool, for the analysis of two power station configuration options, i.e. with a steam feed range and without. Firstly, an investigation into the selection of which computer language to use as a development tool is presented. The Monte Carlo simulation technique is then explained, and simulation models are built of the two power station configurations. The models, which are built using SIMSCRIPT 11.5 simulation language to represent the real world in each configuration option, are then discussed. The availability analysis is developed, and conclusions and recommendations are discussed, as presented in the report to Eskom Management.

Analysis of future alternatives for US utilities is needed as a part of evaluating the impact of combined cycle and phased-construction of integrated coal gasifier power plants on generation expansion. The study encompassed both large and small electric utilities and long-run, least-cost expansion plan for the generating system and studies of the short-run production cost of electrical generation for selected years. The long-run studies were carried out using the Wien Automatic System Planning Package (WASP-II). The optimal combined cycle penetration level was determined for a set of assumptions that involve economics, new technology trends, and feasibility as well as the utility's existing capacity and load forecast. Additional cases were run to account for phased construction and coal gasification. Two electric utilities were selected in this study. These are a U.S. southeastern utility the Bangladesh Electric Utility. The former was chosen as the large utility. The latter was considered a small size utility. WASP-II enhancements enabled us to run cases using IBM-RT and to account for phased construction. The sensitivity studies involved the penetration levels, the fuel supply (oil and natural gas), and economic dispatch of coal gasifiers in particular, and combined cycle power plants in general. Load forecast, and availability of hydroelectric energy were kept uniform. However, adding new power plants and retiring old ones were considered to achieve a more economical and reliable planning strategy while considering issues of technical feasibility. / M.S.

A plan for integrating modeling techniques and improving hydroelectric plant performance is presented. The plan begins with defining and establishing basic plant modeling parameters from the physical plant description. Guidelines for forming linear or nonlinear mathematical models are developed and the plan culminates in the determination of settings for P-I-D control which achieve optimum plant performance. Mathematical models are developed for the hydroelectric plant components -- the penstock, the hydraulic turbine (specifically a Francis turbine), the generator with its connected electrical system, and the control system. A unique method for characterizing turbine performance from a hill diagram is presented. Stability regions for linear models are determined and control settings which result in optimum plant performance are established. Settings associated with high derivative gains are indicated as giving optimum performance when a linear plant model is used. Nonlinear simulations at various operating conditions reveal that less lively gains must be used for the required gate motion to be achievable. For the representative plant model studied, the optimum governor settings resulted in a 7 percent improvement over other recommended P-I-D settings while satisfying gate speed constraints which the other recommended settings violated. The benefit of this work is in an improved ability to develop and utilize appropriate mathematical models for a hydroelectric plant and in the determination of control settings which improve plant performance. / Ph. D.

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This thesis reveals and explores a history of the New Zealand present, providing insight into myths through which New Zealanders shape their perceptions and relationships with the world that surrounds them, and interrogating the concepts that support those myths. This myth referred to is a regime of truth based on perceptions of environmental responsibility, embodied in language, policy, actions, and incorporated into official discourse through imagery, an international government-driven advertising campaign portraying a "100% Pure New Zealand" and institutionalisation. There is a Department of Conservation, a Ministry for the Environment, National Parks and Reserves and a Resource Management Act based on a fundamental principle of sustainable management. Popular discourse also recognises environmental values - hence the appearance of concerted public and media campaigns against proposed development of coastal and timbered areas and the survival of lobby and pressure groups based on environmental causes such as opposition to genetic modification and the alienation of areas considered of natural significance. However, a study of relevant strains of discourse in the New Zealand environmental context reveals ruptures and reversals, inconsistencies and contradictions. The focus and meanings within discourse have changed; the position and power of the environment has been both affected by, and has affected, power relationships. At certain times and in particular social conditions, an environmental voice has been compelled to occupy a space on the outskirts of a dominant discourse and to comply with its discursive practices, as a way of gaining legitimisation. At others, an environmental discourse has gained a fleeting triumph, to be privileged as truth. From the official outset of European colonisation in 1840, a discourse grounded in such modernist values as technological optimism, economic progress and capitalism both framed and legitimised utterances of the colonists and grounded decisions that were to fundamentally and permanently affect the New Zealand physical environment. Themes that were to echo through the years in such discursive enunciations as acclimatisation and engineering were justified on the basis of "progress". Such themes included the presumption that "man" and fulfilment of "his" needs was the ultimate dictate, and that this could and would be achieved through scientific discovery and its application through engineering and arts. Only through such a pursuit could civilisation advance onwards and upwards along a never-ending path. Within such a discourse, Nature had no distinct or valid domain outside that of man, but was merely a storehouse of raw materials, to be dipped into by Man when and where desired. One of the most significant manifestations for New Zealand in the twentieth century of this modernist discourse has been the development of hydro-electricity. The availability of the necessary technology in a country boasting plentiful rainfall, numerous fast-flowing rivers, pockets of population and a tradition of socialist, centralist political philosophy shaped hydro-electricity as a metaphor for New Zealand-style civilisation - enabled and controlled through government decision-making. Consequently, a genealogical study of the discourses relating to hydro-electricity policy and debate can provide valuable insight into the power relations between those exercising power through a modernist discourse and an environmental resistance, and into strategies that were adopted or developed as part of such discourses in the exercise of power. In particular, a detailed study of specific examples permits the interplay of socio-temporal factors and practices to be appreciated. Hydro-electricity is thus the contextual focus selected in this thesis, a focus reflected in the title. The genealogical method involves uncovering and contextualising primary and secondary materials within their historical setting. Through the interrogation of such materials this approach contributes to a critical understanding of power relations and how those relations influence strategies that might be utilised in the exercise of power. Such a method was therefore selected to analyse the tensions implicit in discourse within three historically and contextually specific case studies. These case studies involved in chronological order the proposal to harness the waters of the Bowen Falls in Fiordland during the 1920s, the proposal to raise the level of Lake Manapouri (together with that of the neighbouring Lake Te Anau) in the 1960s, and finally the proposal to divert a large proportion of the mean water-flow of the Lower Waitaki river during the first part of the twenty-first century. A principal conclusion that is reached through the analysis is that the present environmental discourse in New Zealand is not the inevitable outcome of progressive and logical history. Nor can it be explained as chance or as a consequence of world changes, but is a function of power/knowledge. Changes in the regime of truth are therefore the outcome of a successful power strategy exercised by a resistance in challenging that regime of truth. In addition, what might be defined as "environmental discourse" in the New Zealand context is narrowly defined, limited by environmental cause, a cause shaped in turn by the language of conservation. The lesson from history is that the regime of truth of such a discourse is not an end, stable and unchanging for the future, but must be seen rather as brittle, uncertain and vulnerable to attack. A third conclusion that emerges from the hydro-electricity focus is that this particular discursive enunciation of a New Zealand-style modernist discourse was a metaphor for social and economic progress, thereby occupying a privileged position as truth. Finally, one of the important contributions to methodological debate made by the thesis lies in its application of the Foucauldian genealogical method in exploring the general history of a socio-temporal context, thereby uncovering power strategies effected through discourse. This in turn reveals the hidden events, the silent voices and the games played in establishing and challenging a regime of truth.

Thesis (M.S.)--Worcester Polytechnic Institute. / Keywords: nuclear power plant; electric cables; fire. Includes bibliographical references (p. 70-75).