M.Ing. / This thesis considers in detail the applicability to hydro power systems of the theories of steady and unsteady flow in pipelines. In doing so.it highlights some of the shortcomings of these theories. An attempt is made by way of experimentation on a high pressure pipeline, to model some of the conditions which could occur in a full size future hydro power system. These experiments provide some quantitative data about the performance of some typical hydro power components such as pipes, orifices and valves, under steady and unsteady conditions. A computer program is included which was used to provide theoretical data to compare with the experimental results. The program was found to be limited in its capacity to provide accurate simulation of the experimental pipeline, but this was thought to be due to the pipeline not correctly modelling a hydro power system. Conclusions presented in this thesis will be of assistance to designers of future hydro power systems and to researchers continuing this work.

M.Sc. / The increased demand for electricity in South Africa is expected to exceed supply between 2004 and 2007. Electricity supply options in the country would be further complicated by the fact that older power stations would reach the end of their design life beyond the year 2025. In light of this and considering the long lead times required for the commissioning of new plants, new power supply options need to be proactively investigated. The environmental impacts associated with coal-fired generation of electricity have resulted in increased global concern over the past decade. To reduce these impacts, new technologies have been identified to help provide electricity from fossil fuels. The alternatives considered are gas-fired generation technologies and the Integrated Gasification Combined Cycle (IGCC). This study attempts to document and understand the environmental aspects related to gas-fired and IGCC electricity generation and evaluate their advantages in comparison to conventional pulverised coal fired power generation. The options that could be utilised to make fossil fuel electricity generation more environmentally friendly, whilst remaining economically feasible, were also evaluated. Gas-fired electricity generation is extremely successful as electricity generation systems in the world due to inherently low levels of emissions, high efficiencies, fuel flexibility and reduced demand on finite resources. Associated benefits of a Combined Cycle Gas Turbine (CCGT) are lower operating costs due to the reduced water consumption, smaller equipment size and a reduction in the wastewater that has to be treated before being returned to the environment. A CCGT plant requires less cooling water and can be located on a smaller area than a conventional Pulverised Fuel (PF) power station of the same capacity. All these factors reduce the burden on the environment. A CCGT also employs processes that utilises the energy of the fuel more efficiently, with the current efficiencies approaching 60%. Instead of simply being discharged into the atmosphere, the gas turbines’ exhaust gas heat is used to produce additional output in combination with a Heat Recovery Steam Generator (HRSG) and a steam turbine. Furthermore, as finite resources become increasingly scarce and energy has to be used as wisely as possible, generating electricity economically and in an ecologically sound manner is of the utmost importance. The clean, reliable operation of gas-fired generation systems with significantly reduced noise levels and their compact design makes their operation feasible in heavily populated areas, where electricity is needed most. At the same time, energy can be consumed in whatever form needed, i.e. as electricity, heat or steam. The dependence of the South African economy on cheap coal ensures that it will remain a vital component of future electricity generation options in the country. This dominance of coal-fired generation in the country is responsible for South Africa’s title as the largest generator of carbon dioxide (CO2) emissions on the continent and the country could possibly be requested to reduce its CO2 emissions at the next international meeting of signatories to the Kyoto Protocol. Carbon dioxide emissions can be reduced by utilising gas-fired generation technologies. However, the uncertainty and costs associated with natural gas in South Africa hampers the implementation of this technology. There are currently a number of initiatives surrounding the development of natural gas in the country, viz. the Pande and Temane projects in Mozambique and the Kudu project in Namibia, and this is likely to positively influence the choice of fuel utilised for electricity generation in the future. The economic viability of these projects would be further enhanced through the obtaining of Clean Development Mechanism (CDM) credits for greenhouse gases (GHG) emissions reduction. Alternatively, more efficient methods of generating electricity from coal must be developed and implemented. IGCC is capable of achieving this because of the high efficiencies associated with the combined cycle component of the technology. These higher efficiencies result in reduced emissions to the atmosphere for an equivalent unit of electricity generated from a PF station. An IGCC system can be successful in South Africa in that it combines the benefits of utilising gas-fired electricity generation systems whilst utilising economically feasible fuel, i.e. coal. IGCC systems can economically meet strict air pollution emission standards, produce water effluent within environmental limits, produce an environmentally benign slag, with good potential as a saleable by-product, and recover a valuable sulphur commodity by-product. Life-cycle analyses performed on IGCC power plants have identified CO2 release and natural resource depletion as their most significant positive lifecycle impacts, which testifies to the IGCC’s low pollutant releases and benign by-products. Recent studies have also shown that these plants can be built to efficiently accommodate future CO2 capture technology that could further reduce environmental impacts. The outstanding environmental performance of IGCC makes it an excellent technology for the clean production of electricity. IGCC systems also provide flexibility in the production of a wide range of products including electricity, fuels, chemicals, hydrogen, and steam, while utilizing low-cost, widely available feedstocks. Coal-based gasification systems provide an energy production alternative that is more efficient and environmentally friendly than competing coalfuelled technologies. The obstacle to the large-scale implementation of this technology in the country is the high costs associated with the technology. CDM credits and by-products sales could possible enhance the viability of implementing these technologies in South Africa.

This thesis offers a review and an analysis of all except the less important advances of the previously developed methods and equations for optimizing the operation of an electric system of m thermal and n hydro plants. In this analysis both short-range (twenty-four hours, seven days) and long-range (one year) periods are involved. The primary objective of this thesis is to derive, using the Calculus of Variations, general differential equations for short-range optimization of combined hydro-thermal systems. The basic criterion for choosing to solve the short-range instead of the long-term problem lies in the theory of forecasting in general, the theory of forecasting of stream flows in particular, and is based on the aforementioned analysis. Tests for establishing the fact that the above general equations actually produce the desired minimum cost of operation are given in the form of three other necessary conditions and three sufficient conditions. These conditions are known in this branch of mathematics as the analogue of Legendre's condition, the Weierstrass’ analogue of the Jacobi's condition and the Weierstrass' E-function condition for a minimum. A well-known example is worked out using these conditions. In addition to the above, this thesis also proves that all previously developed methods and equations for short-term optimization are essentially equivalent, and that these formulas are merely simplified forms of the general equations developed in this treatise. / Applied Science, Faculty of / Electrical and Computer Engineering, Department of / Graduate

Hydroelectric power has traditionally been the object of much publicity in the Soviet Union, yet few facts are available regarding the significance of hydro to the electricity industry on a national, and especially on a regional, basis. This thesis seeks to clarify the situation in determining the significance of Soviet hydro potential as well as existing hydro capacity on both national and regional levels. In so doing a system of regions based on power networks has been used and for these regions total installed generating capacities have been calculated so as to provide a basis for quantitative ranking. This study is not concerned simply with the generation of electricity, but with estimating absolute size and type of regional installed capacity and generation, together with the heretofore neglected aspect of consumption. A different approach to evaluating the importance of consumers of electricity is advocated, one in which load factor plays an important role and required KW capacity to meet a particular demand constitutes the prime criterion. The result has been to emphasize the spatial variations in complementary aspects of the Soviet electricity industry. It was found that the concepts most frequently used in assessing Soviet hydro potential have certain limitations, the most important being a neglect of relative distribution. By considering the distribution of remaining prospective dam sites in terms of "economically accessibility," it has been possible to reduce the figure for Soviet hydro potential by almost one-half. While it has been shown that there has been a movement eastward and therefore greater correlation between hydro capacity and hydro potential at present, including hydro capacity currently being installed, almost a third of the "economically accessible" hydro potential is now utilized. For many years there has been concern over meeting system peak load demand economically and in this context hydro capacity in many regions has assumed the function of meeting peak load demand, especially during the winter months. The Central Siberian region has not as yet realized the full benefit of the large scale projects, both hydro and thermal, thus far undertaken and at present is not characterized by low cost electricity. A decreasing average cost can be expected during the next few years. While traditionally viewed as a source region of electricity it has been determined that a possible export of 15-20 percent of total regional generation would have only a limited impact if exported to European Russia. It can be expected that this region will prove to be attractive in the location of electricity intensive industry. It is the concensus here also that large scale hydro construction will continue, but at a slower pace. The demand for electricity in Central Siberia is not yet characterized by any particular industry or sector. In the future aluminum production will constitute an important share of total demand for electricity in this region. The one feature common to the four regions of European Russia is a dependence to a greater or lesser degree on external sources of energy for the generation of electricity. While emphasis has been placed on the utilization of local energy resources, insofar as hydro is concerned, little can be expected as over 80 percent of potential has now been utilized. To date the Urals and Center-Volga have experienced the most serious power shortages, due primarily to the high degree of industrialization and heavy concentration of urban population respectively. The South in contrast does not appear to be in the same situation, the result both of its broader energy resource base and a more diversified demand. The Northwest region while scheduled to be interconnected with the Unified European Power Network, lacks any distinguishing feature in its electricity industry and will remain of peripheral importance. Within what have been referred to as the Peripheral Regions there exists considerable "economically accessible" hydro potential. However, much of this is likely to remain undeveloped for many years to come, especially in the Far East. In the Caucasus and Central Asia, while hydro has traditionally provided the bulk of electricity, in recent years gas-fired thermal stations have made striking inroads. In the Caucasus limited gas reserves will of necessity force the region to look to external sources if this trend is to continue. This is not a problem in Central Asia where there exists extensive gas reserves. Of the remaining regions, Northeast Kazakhstan and Murmansk, only the former is scheduled to assume significance on the national level. / Arts, Faculty of / Geography, Department of / Graduate

This thesis examines the influence of different degrees of serial correlation in the streamflow records on optimal operation of a hydroelectric reservoir. This thesis also investigates the practical aspects of choosing different decision variables, considering effects on ease of implementation, total benefit, and actual use for real-time operations. Stochastic dynamic programming was used to optimize the long-term operation of a hydroelectric project with a single reservoir. Reservoir inflows were analyzed using monthly flow record for 58 years with the assumption that monthly inflows are either perfectly correlated, uncorrelated, or partially correlated. Reservoir level change and powerhouse discharge were considered as alternative decision variables for each of the three cases of inflow serial correlation. The optimization results were then examined and compared to determine the significance of the choice of decision variables and to explore the effects of inflow serial correlation on practical operating decisions which might be based on the results of the optimization. It was found that (1) Case 2 in which inflows were assumed perfectly correlated and Case 3 with partially correlated inflows produce, respectively, highest and lowest total expected return, (2) the difference in total expected return between cases depends largely upon the physical characteristics of the system, (3) the reservoir level change decision case produces more conservative results than the discharge decision case, (4) the results from the reservoir level change decision are easier to use for realtime operation than those from the discharge decision case, (5) different results will be produced with different choice of decision variables. / Applied Science, Faculty of / Civil Engineering, Department of / Graduate

Master of Science

The inspection of deep and long, water-filled tunnels at pumped storage hydroelectric stations has posed a challenge to the electric utility industry. Virginia Power and its partner, Allegheny Power System, faced this challenge at its Bath County Pumped Storage Station in western Virginia. <p>Bath County is the largest station of its kind in the world with a combined generating capacity of 2100 megawatts. The station consists of six pump/turbines and three large tunnels, each 28.5 feet in diameter and approximately two miles long, which link the upper and lower reservoirs. <p>After reviewing the alternatives of using divers, manned submersibles and dewatering of the tunnels, the owners decided to use a submersible remotely operated vehicle (ROV) for the inspection task. A study was performed which determined that the owners could save approximately $677,000 by performing the work in-house versus hiring a specialty contractor. <p>An ROV system was developed and equipped specifically for tunnel inspection work. Three video cameras, a stereo photo camera, dye release system, dual head sonar, and a 7000 foot umbilical provided the inspection capabilities. <p>The overall condition of the tunnels was very good, particularly in the upper and lower horizontal sections. The vertical flow shaft of the tunnel had two predominant longitudinal cracks with the east wall crack showing evidence of water egress. <p>The ROV system proved to be a very safe, economical, and reliable means of conducting inspections of this type. The vehicle successfully completed the 6100 foot excursion at a maximum depth of 1350 feet, representing the longest tunnel excursion performed to date. It is probable that inspections of this type will become the norm at hydroelectric stations as well as other facilities with similar tunnel systems requiring inspection. <p>This report will describe the background of the project, discuss the evaluation of inspection alternatives. and provide a complete description of the HYDROVER system and its development. A brief discussion of the results of the inspection of the first of the three tunnels will be presented. Although portions of the remaining two tunnels have now been inspected, these results are not within the scope of this paper. <p>Following the discussion of the system development and inspection results, conclusions will be presented regarding the viability and future role of this advanced underwater technology. / Master of Engineering

Master of Science

No description available.

A research report submitted to the Faculty of Science, University of the Witwatersrand, Johannesburg, in partial fulfilment of the requirements for the degree of Master of Science, Joannesburg, 2014. / An investigation was performed to look at a method to develop easy to use field survey measurements to assist decision makers in the process of deriving public protective actions. This method could be used at a nuclear power plant if certain accident conditions are known. International values for operational intervention levels (OIL’s) do exist and are recommended to be employed if station specific data has not been derived. No values exist specific to Koeberg Nuclear Power Station and as a result, this became an ideal opportunity to derive station specific values. It was firstly necessary to decide on a specific accident type and hence an applicable accident release fraction. A suitable accident software dispersion code was applied to calculate the organ doses for the selected accident type. It was also decided to use two different wind dispersion criteria to further refine the results. Due to the complexities of dose distribution within the body it was also necessary to look at the gamma dose in isolation as this would be the measurement radiation type utilised as a limit in the field either using installed radiation monitors or by physical measurement performed by station Radiation Protection staff. Comparisons were done with thyroid and lung dose versus gamma dose to arrive at ratios for this specific accident type. This would then be indicative of the total dose to each organ as a result of a single field measurement. Conclusions were drawn on the results obtained and recommendations were made for when this type of data may be suitable for use in the unlikely event of a nuclear accident.