The master‘s thesis deals with the issue of weak points of the distribution network in a municipality with high numbers of photovoltaic sources. Photovoltaic power plants are gradually being added to the current state of the electric power distribution network of a specific municipality, while changes in the network are being monitored. Due to the output of the highest possible power from the sources into the distribution system in compliance with the established rules, the thesis also describes network modifications. These established rules of connection and operation of resources in the distribution network and effects of injecting disturbances in the low voltage network are discussed in the theoretical part of the thesis.

As the power systems grow, system connections become more complex. Due to cost and environmental concern, more and more parallel lines and series compensated lines may be installed in the system. In order to efficiently use the transmission network, more nonlinear flexible devices such as the phase shifter and the advanced compensation system will be put into use. Once a fault occurs on such a system, a delay in clearing the fault is usually not permissive. This requires a new generation of relays which have high security and dependability and high operating speed. With the advent of high speed microprocessor and fiber optic communication technologies, it is possible to develop high performance relays. In this dissertation, a new generation of pilot relays and non-pilot relays were developed for a transmission line. The pilot relays include the instantaneous percentage current differential (IPD), the phase comparison and the phasor based percentage current differential (PPD) principles. In the pilot protections the synchronized phasor measurement techniques are employed and digital CT saturation detectors are incorporated. All these schemes in primary protections feature charging current (or shunt current ) compensation. The phasor based principles are designed to work within one and a half cycles; while others based on sample by sample comparison are assumed to work in less than a cycle. The non-pilot relays to be investigated in this dissertation include the fault location based and phase angle based directional distance relays. One cycle data window is used in the phasor calculation. Both the distance relays are assumed to make a trip decision in about one and a half cycles. All algorithms were simulated against different fault conditions using EMTP outputs. The simulation results show all the pilot relay algorithms work well for EHV IUHV transmission lines including the series compensated lines. The fault location based distance relay works well in most cases, but it may give a wrong decision for the close-in fault with the fault resistance and may have a singularity problem. The phase angle based distance relay works very well for different fault conditions and is insensitive to fault resistance. The modified phase angle based distance relay was also developed for the series compensated line. It would not lose the direction for faults with or without fault resistance, either for a compensated system in forward direction, or in an adjacent line in reverse direction. The overreach is within 20% of the protected zone. This relay algorithm is also based on the one-cycle data window DFT, and it can give a reliable trip decision in about two cycles. All pilot relays with a fiber optic link and the phase angle based distance relay can constitute a new generation of protection systems for EHV IUHV transmission lines. / Ph. D.

The effects of interphase coupling in a multiphase power system become important in the presence of network imbalances and unbalanced phase loadings. In grounded-wye systems, currents that flow in the earth can have significant effects on the system's behavior. Both these effects must be considered in an accurate multiphase power system model. A new treatment of multiphase power system modeling is presented. The treatment relies upon linear graph theory and produces a system multiport model. Mutual coupling effects, the effects of neutral and static conductors, the finite conductivity of earth, and various component models are considered. A reduction in the order of the multiport model also is presented. Multiphase load flow analysis is introduced. Special considerations that arise in multiphase analyses are discussed. Example solutions are presented. A convenient method of representing multiple slack ports is described which results from an application of the principle of superposition. Circulating power flow in multiphase loops is discussed. A procedure is proposed for conveniently representing common shunt and series faults that occur in power systems. The procedure is constructed for efficient computer modeling of multiple cases of various fault combinations in a particular system. / Doctor of Philosophy

As the load on the power system grows and new transmission facilities become increasingly difficult to build, the utilities must look to ways to make the most of the current transmission system. Adaptive relaying is one way to enhance the ability of the power system. On the Florida - Georgia interface an adaptive out-of-step relay is being installed. This relay determines if swings on the power system will remain stable by performing a better then real-time transient stability study. Because of the computing capacity required for a transient stability study, the study cannot be performed on the full power system. A reduced model must be used. In this thesis, various methods of obtaining reduced models for use in the relay will be explored. The models will be verified with a full system model using Electric Power Research Institute's (EPRI) Extended Transient-Midterm Stability Package (ETMSP). / Master of Science

[Abstract - Conclusion]: This research study confirms the theory in the literature review on delivery of quality service to customers and premise that there is a statistically significant difference between Eskom service as perceived by rural prepaid household customers and their expectations. This study also highlights the need for Eskom management to take into cognisance the unique rural prepaid customer service needs and how to meet them, perhaps a differentiated service approach rather than a one-strategy-fits-all approach. This is in view of gaps created between expectations and perceptions of service, especially in the reliability dimension that could require a concentrated or changed performance approach to close them.

Thesis (M. Tech. Electrical engineering) -- Central University of technology, Free State, 2012 / Infrared thermography is a non-contact method of identifying the thermal behaviour of various plant equipment and machines, including their components, qualitatively via pattern recognition and quantitatively via statistical analysis. This allows for the development of condition monitoring and predictive failure analysis. It is well established that optimized maintenance planning can be more effective when a problem is detected in the early stages of failure. For example, in electrical systems an elevated electrical resistance caused by loose or corroded connections, broken conductor strands and dirty contact surfaces, results in localized heating, and a unique infrared pattern when analysed leads to the location of the problem and an indication of its severity. In recent years industrial thermography has used infrared detectors in the long wave portion of the electromagnetic spectrum normally between 8μm and 15μm, due partly to the fact that these wavelengths are not susceptible to solar radiation and/or solar glint. A number of scientific experiments were carried out on test apparatus to improve the understanding of the impact of convection, ambient air temperature and relative humidity on resultant infrared thermal images. Two similar heat sources, simulating a hotspot, at different temperature settings were used to determine whether the hotspot temperature should also be considered in conjunction with the atmospheric elements. The need for these experiments has also been identified by EPRI (Electrical Power Research Institute) in the USA as necessary to develop international severity criteria, and it is hoped that this study will contribute to this goal.

Thesis (MBA)--Stellenbosch University, 2000. / ENGLISH ABSTRACT: The South African Electricity Distribution Industry is riddled with tariffs. Every utility in South Africa probably uses some method for allocating cost, whether it is theoretically founded or not. There are currently over 2000 different tariffs in South Africa and the need for rationalisation has been widely recognised and acknowledged. Many of these tariffs have not been the outflow of accepted methodologies but rather a function of individual utility policy and practices. There is however a dire need to standardise such methodologies in the future. A standardised methodology might be the only way to eventually rationalise the thousands of tariffs that exist in the electricity industry. Government has emphasised the importance of tariffs to be cost reflective in the future. The only possible way to reach this objective would be to determine clear and concise methods of allocating cost that can be utilised by the entire industry. This study project describes a standardised methodology for determining the cost to supply different customer categories in an electricity distributor. The methodology offers enough flexibility not to bind any party into laboursome, complex and time consuming costing activities. It does however require that the costs of a distributor are carefully investigated and all functions performed in the utility are isolated. This is referred to as ringfencing of costs. / AFRIKAANSE OPSOMMING: Die Suid-Afrikaanse Elektrisiteitverspreidingsbedryf het veelvuldige tariewe. Elke utiliteit in Suid-Afrika gebruik waarskynlik 'n metode vir kostetoedeling, wat nie noodwendig teoreties gebaseer is nie. Huidiglik is daar meer as 2000 verskillende tariewe in Suid-Afrika en dit word alom besef en erken dat gronde vir rasionalisering bestaan. Baie van die tariewe het nie ontstaan uit die gebruik van aanvaarbare berekeningsmetodes nie, maar was eerder die gevolg van individuele beleid en praktyke van utiliteite. Daar is 'n dringende behoefte om hierdie berekeningsmetodes in die toekoms te standardiseer. 'n Standaard metode mag die enigste manier wees om uiteindelik die duisende tariewe wat in die elektrisiteitsbedryf bestaan te rasionaliseer. Die regering het die belangrikheid dat tariewe in die toekoms koste reflekterend moet wees benadruk. Die enigste moontlike manier om hierdie doelwit te bereik, is om helder en duidelike metodes vir koste toedeling te bepaal vir gebruik deur die hele bedryf. Hierdie verhandeling beskryf 'n standaard metodologie om die koste te bepaal om verskillende klantegroepe in 'n elektrisiteitsverspreider van krag te voorsien. Die metodologie bied voldoende plooibaarheid om geen party aan arbeidintensiewe, kompleks en tydrowende kostebepalings te verbind nie. Dit vereis egter dat die koste van 'n verspreider noukeurig ondersoek word en dat alle funksies wat verrig word uitgelig word. Hierna word verwys as afbakening van kostes.

Thesis (MBA)--University of Stellenbosch, 2010. / Climate change is one of the most serious issues the world is facing today. With an economic slowdown globally, huge food shortages and record-high fuel prices, it has never been so important for countries to guard their natural resources to ensure future sustainability. The South African energy generation industry, of approximately 40 000 Mega Watt (MW), consists largely (90%) of coal-fired power stations, with the remainder comprising of nuclear and pumped storage schemes which are regarded as environmentally neutral. It is only recently that Eskom and independent power producers (e.g. Darling Independent Power Producer Wind farm with an estimated 10 MW) embarked on utilising South Africa's natural resources to generate electrical power. South Africa's access to inexpensive coal and paid off coal-fired power stations has made it difficult to justify the investment in renewable energy. However, on 31 March 2009 South Africa became the first African country to introduce a feed-in-tariff for renewable energy (Gipe, 2009). The hope is that this initiative would stimulate the investment in green energy generation. Eskom and municipalities are currently the only entities that have licences from the National Energy Regulator of South Africa (NERSA) to buy bulk electricity from power producers. The question therefore arises: if green electricity is more expensive to generate and is sold at a price premium to Eskom and municipalities, would they pass the premium on to consumers; can they differentiate the green electricity product and will consumers be willing to buy at a premium price? This research study aims to answer if businesses would be willing to pay a premium for green electricity, why they would be willing to buy it, which factors influence the purchasing decision and what barriers exist that will deter a purchase. A survey was conducted on businesses in the Western and Northern Cape of South Africa. The businesses sampled have a notified maximum demand of 50kVA or higher and excludes the re-distributor (City of Cape Town) customers. Approximately ten per cent of businesses would be willing buy green electricity. Most of these businesses have indicated that they are willing to pay a premium of five to nine per cent for green electricity. The businesses that are willing to pay the largest premiums (>10%) are in the electricity, gas, water, finance, insurance, real estate, business services, manufacturing, transport, storage and communications sector. Businesses that are willing to buy green electricity: • Have a strategy to reduce their carbon footprint; • Want to be community leaders (altruistic motivators); • Have as their biggest barrier the additional cost of green electricity; and • Feel that power utilities should be required to include a minimum percentage of green energy in their energy mix.

Thesis (MBA (Business Management))--University of Stellenbosch, 2009. / ENGLISH ABSTRACT: The purpose of this study is to determine whether residential electricity consumers within the Cape Peninsula would be willing to voluntarily purchase green electricity if it is sold at a premium price. International experience in the field of green marketing shows that while niche markets for green electricity clearly existed, few programmes however exceeded a 5% penetration in the residential market. This study therefore methodologically drew on recent development in the literature of norm-motivated behaviour to identify testable factors that could influence residential consumers’ willingness to purchase premium-priced green electricity. After identifying these core testable factors, they were used to test various hypotheses. This was done through the testing of primary data that was collected through a telephone market survey of 405 respondents within the Cape Peninsula. These respondents were all identified as financial decision makers within their electricity consuming households. This study subsequently found that residential electricity consumers in the Cape Peninsula are very concerned about the future of the environment and that a large percentage of them (more than 40%) from almost all income levels might voluntary buy premium-priced green electricity. However, as it did identify that consumers must truly be convinced of the positive effects that green electricity would have on the environment before voluntarily supporting such a campaign, it found that consumers might not be well enough informed on environmental and climate change issues to ensure their actual support. To be at all successful, such a green electricity marketing campaign should be very informative and specifically focused on the positive effects that such a purchase would have on the environment. This study also found that supportive residential consumers would on average be willing to pay a maximum premium of 26% or approximately 15c/kWh. The combined maximum potential value of these premiums amount to R39 million per month. This serves as indication that there is much room for future development of the green electricity market. This study also identified that the majority of residential consumers believe that excessive users of electricity should be forced to make a larger financial contribution towards the generation of green electricity than low usage consumers. Based on its findings, the study closes with recommendations to role players in the green electricity market, i.e. the City of Cape Town Municipality, Darling Wind Farm and Eskom. / AFRIKAANSE OPSOMMING: Die doel van hierdie studie is om te bepaal of residensiële elektrisiteitsverbruikers in die Kaapse Skiereiland gewillig sou wees om vrywilliglik groen elektrisiteit teen ’n premie aan te koop. Internasionale ervaring op die gebied van groen elektrisiteit het getoon dat, alhoewel daar verseker nismarkte vir groen elektrisiteit bestaan, baie min programme meer as 5% van die residensiële mark kon wen. Hierdie studie steun dus metodologies op onlangse verwikkelinge in die literatuur rakende normgemotiveerde gedrag om sodoende toetsbare faktore te identifiseer wat moontlik verbruikers se bereidwilligheid om groen elektrisiteit teen ’n premie te koop, kan verbeter. Na die identifisering van hierdie toetsbare faktore is hulle gebruik om verskeie hipoteses te toets. Dit is gedoen deur die toets van primêre data wat deur middel van telefoon-marknavorsing by 405 respondente binne die Kaapse Skiereiland ingesamel is. Hierdie respondente was almal geïdentifiseer as finansiële besluitnemers van huishoudings wat elektrisiteit gebruik. Hierdie studie het bevind dat residensiële elektrisiteitsverbruikers in die Kaapse Skiereiland baie besorg is oor die toekoms van die omgewing en dat ’n groot hoeveelheid van hierdie huishoudings (meer as 40%) van amper alle inkomstegroepe moontlik gewillig sou wees om groen elektrisiteit teen ’n premie aan te koop. Die studie het ook bevind dat omdat hierdie bereidwilligheid van die residensiële verbruikers onderhewig is aan hul oortuiging dat groen elektrisiteit ’n werklike positiewe effek op die omgewing uitoefen, residensiële verbruikers dalk huidiglik nie werklik goed genoeg ingelig is rakende omgewingsbewaring- en klimaatsveranderingskwessies nie. Hierdie gebrek aan kennis kan dus moontlik hul bereidwilligheid om groen elektrisiteit teen ’n premie aan te koop, negatief beïnvloed. Om suksesvol te wees sal groen elektrisiteit-bemarkingsveldtogte baie volledige inligting moet verskaf en sterk gefokus moet wees op die omgewingsvoordele wat die aankoop van groen elektrisiteit inhou. Die studie het ook bevind dat residensiële ondersteuners bereid sou wees om gemiddeld ’n maksimum premie van 26% of 15c/kWh te betaal. Die gesamentlike maksimum potensiële waarde van hierdie premies is R39 miljoen per maand wat daarop dui dat daar heelwat ruimte mag wees vir toekomstige uitbreiding van die mark vir groen elektrisiteit. Hierdie studie het ook geïdentifiseer dat die meerderheid residensiële elektrisiteitsverbruikers glo dat oormatige elektrisiteitsverbruikers gedwing moet word om ‘n groter finansiële bydrae tot die opwekking van groen elektrisiteit te maak as lae elektrisiteitsverbruikers. Gebaseer op die bevindinge van hierdie studie, sluit dit af met aanbevelings tot verskeie rolspelers in die mark vir groen elektrisiteit, soos die Kaapstadse Munisipaliteit, Darling Windplaas en Eskom.

Thesis (MBA)--Stellenbosch University, 2002. / ENGLISH ABSTRACT: The energy sector of the South African economy is poised to change in extraordinary ways. In just a few short years from now, the days will be gone when generators are guaranteed of their income and where regional distributors have the monopoly in the regions that they are servicing. Other energy markets in the world, such as oil and gas, have been free of regulation for many years. More recently, local policymakers have been focussing on increasing competition in the electricity sector and in so doing, liberate electric utilities from government's long established control. The shift away from government regulation of energy will lead to something even more important than placing downward pressure on the price of a MWh. It will instigate the development of multiple trading centres and platforms that are dedicated to competition in the free trade of electricity and related products. With the deregulation of the electricity supply industry and the inevitable introduction of competition, the real risks of energy trading will be faced by generators and distributors alike. This research investigates the changes that are set to occur within the next few years, based on developments that have unfolded in countries where electricity supply industries have been privatised and utilities and distributors are managing their risks in this new competitive environment. It explains how the South African Electricity Supply Industry may change with respect to the develop of markets which provide risk cover to industry players, the practices assumed by utilities in international electricity supply industries to minimise their risk exposure, and how industry players can use derivative instruments to manage their risks better. / AFRIKAANSE OPSOMMING: Die elektrisiteitsvoorsieningssektor is gereed om groot veranderings te maak. Binne 'n paar jaar, sal ons die einde sien van die dae waar kragstasies gewaarborg is van hulle inkomste en waar streeksvoorsieners die monopolie het in die streke waarin hulle verskaf. Ander energie markte in die wêreld, soos die van olie en natuurlike gas, is al sonder regulering vir baie jare. Meer onlangs het beleidsrade hul tyd toegewy aan die instelling van kompetisie in die elektrisiteitsvoorsieningssektor om utiliteitsmaatskappye vry te maak van staatsbeheer. Hierdie beweging weg van staatsbeheer sal lei na iets meer as net die afwaardse druk op die prys van 'n MWh. Dit sal die begin merk van die ontwikkeling van veelvoudige verhoë wat toegewyd is aan kompetisie in die vrye handel van elektrisiteit en soortgelyke produkte. Met die deregulering en die onvermydelike indiening van kompetisie, sal die ware risikos van energie handel aanvaar word deur voortbrengers en verskaffers van elektrisiteit. Hierdie navorsing stel ondersoek in die veranderings wat van plan is om te gebeur in die volgende paar jaar en is gebaseer op die ontwikkelinge wat in lande afgespeel het waar elektrisiteitsvoorsieningsnywerhede geprivatiseer is en waar voortbrengers en verskaffers van elektrisiteit hulle risikos bestuur in hierdie nuwe mededingende sektor. Dit verduidelik hoe die Suid-Afrikaanse elektrisiteitsvoorsieningsnywerheid mag verander teen opsigte van die ontwikkeling van markte wat risiko versekering aanbied vir utiliteitsmaatskappye, die praktyke wat deur hierdie spelers toegepas word om hulle blootstelling aan risikos te verminder, en ook hoe hulle afgeleide instrumente gebruik om hulle risikos beter te bestuur.