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The impact on demand resulting from an electricity price increase is unknown, Dekenah, Heunis, Gaunt and Cheek (2003). This study focused on large Eskom customers (industry and mining) and the impact of increased electricity prices (Eskom Megaflex Time-of-Use tariff) on their electricity demand is analysed. Since, the impact of this can be only be realised in the long-run (> 5 years), this study made use of historical data. In particular, the impact of the revised Megaflex tariff in 2002, which increased high season (winter) peak active charges by approximately 40% against an approximate reduction of 30% in the low season (winter) was analysed. It was found that the price elasticity of large Eskom customers is inelastic in the short-run (< 2 years) and elastic in the long-run. This is particularly evident in the Manufacturing sector. Furthermore, it was found that price is not the only input cost in the short-run, but economic factors such as commodity prices also influence consumption behaviour. This is particularly evident in the Mining sector. It was also found that alternatives (i.e. mandatory and voluntary load reduction programmes, etc.) impact electricity load profiles. In conclusion, this study found sufficient evidence in support of the research hypothesis. Copyright / Dissertation (MBA)--University of Pretoria, 2010. / Gordon Institute of Business Science (GIBS) / unrestricted

Energy is of concern for governments and economies all over the world. As conventional methods of energy production are facing the prospect of depleting fossil fuel reserves, economies are facing energy risks. With this tension, various threats arise in terms of energy supply security. A shift from intensive fossil fuel consumption to alternative energy consumption combined with the calculated use of fossil fuels needs to be implemented. Using the energy radiated from the sun and converted to electricity through photovoltaic energy conversion is one of the alternative and renewable sources to address the limited fossil fuel dilemma. South Africa receives an abundance of sunlight irradiance, but limited knowledge of the implementation and possible energy yield of photovoltaic energy production in South Africa is available. Photovoltaic energy yield knowledge is vital in applications for farms, rural areas and remote transmitting devices where the construction of electricity grids are not cost effective. In this study various meteorological and energy parameters about photovoltaics were captured in Port Elizabeth (South Africa) and analyzed, with data being recorded every few seconds. A model for mean daily photovoltaic power output was developed and the relationships between the independent variables analyzed. A model was developed that can forecast mean daily photovoltaic power output using only temperature derived variables and time. The mean daily photovoltaic power model can then easily be used to forecast daily photovoltaic energy output using the number of sunlight seconds in a given day.

A test method is developed to measure the equivalent (driving point) positive sequence impedance, as a function of frequency, of an operating power system. The technique used is to apply a phase-to-phase fault at the system node of interest and record the transient voltage across and current in the fault. These quantities are then transformed into the frequency domain. The system driving point impedance is then taken as the ratio of the fault voltage to the current at each point in the frequency domain. Field results from a phase-to-phase fault at a central location on the B.C. Hydro 500 k-V network are presented and analysed to determine the system driving point impedance. The measured impedance versus frequency characteristic is compared with a predicted impedance characteristic based on an Electro-Magnetic Transient program study of a detailed model of the major B.C. Hydro transmission and generation. Correlation between the measured and calculated impedance is good, with explanations offered for any localized significant disagreement. The explanations offered are subsequently verified by Ontario Hydro's improvements to the analysis of the test data and additions to the computer model data. / Applied Science, Faculty of / Electrical and Computer Engineering, Department of / Graduate

This thesis describes a method for determining weak nodes in power systems which may cause divergence in Newton-Raphson loadflow methods. When divergence occurs in production loadflow programs, information related to the cause of divergence is not available. The "Weak Node Method" of this thesis provides such information by identifying one or more weak nodes. The development of the Weak Node Method required extensive experimentation with the Newton-Raphson method. The behaviour of the vectors and matrices of the Newton-Raphson method during divergence are discussed in an effort to familiarize the reader with observed trends. These trends suggested the techniques which comprise the Weak Node Method. With this method, a "quasi" solution is sought first, and, secondly, three analysis procedures are then used to pinpoint the weak nodes. The method was tested using three test cases which would normally have caused the Newton-Raphson loadflow method to diverge. / Applied Science, Faculty of / Electrical and Computer Engineering, Department of / Graduate

New, fast and reliable algorithms for solving load-flow problems are presented in this thesis. Each of these algorithms iteratively solves a set of linear equations in terms of voltage magnitude squared and phase angles, and converges onto the final solution in a few iterations. Although the line losses of the system are used in deriving the equations of the basic line-loss load-flow algorithm, knowledge of their (approximate) values is not a prerequisite to using the algorithm. The basic line-loss load-flow algorithm is slightly modified to give an incremental-change line-loss algorithm which proves to be always preferable to the basic algorithm. By exploiting the weak interdependence between active power and voltage magnitude, and between reactive power and phase angle, two decoupled versions of the incremental-change line-loss algorithm were also developed. All these algorithms have constant gradient characteristics, and their storage requirements are, at most, the same as those of the standard Newton-Raphson algorithm. If need be, the storage requirements can be reduced to those of the triangularized Y-matrix iterative algorithms. Tests on various systems indicate fast and reliable convergence characteristics better than those of the Newton-Raphson algorithm and comparable, to those obtained by Stott and Alsac with their decoupled Newton-Raphson load-flow algorithm. / Applied Science, Faculty of / Electrical and Computer Engineering, Department of / Graduate

Power systems

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