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Thesis. 1978. Ph.D.--Massachusetts Institute of Technology. Dept. of Electrical Engineering and Computer Science. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING. / Bibliography: leaves 248-250. / Ph.D.

The objective of the proposed research is to analyze automated residential energy management technology using primary energy source utilization. A residential energy management system (REMS) is an amalgamation of hardware and software that performs residential energy usage monitoring, planning, and control. Primary energy source utilization quantifies power system levels impacts on power generation cost, fuel utilization, and environmental air pollution; based on power system generating constraints and electric load. Automated residential energy management technology performance is quantified through a physically-based REMS simulation. This simulation includes individual appliance operation and accounts for consumer behavior by stochastically varying appliance usage and repeating multiple simulation iterations for each simulated scenario. The effect of the automated REMS under varying levels of control will be considered. Aggregate REMS power system impacts are quantified using primary energy source utilization. This analysis uses a probabilistic economic dispatch algorithm. The economic dispatch algorithm quantifies: fuel usage and subsequent environmental air pollution (EAP) generated; based on power system generating constraints and electric load (no transmission constraints are considered). The analysis will comprehensively explore multiple residential energy management options to achieve demand response. The physically-based REMS simulation will consider the following control options: programmable thermostat, direct load control, smart appliance scheduling, and smart appliance scheduling with a stationary battery. The ability to compare multiple automated residential energy management technology options on an equal basis will guide utility technology investment strategies.

Thesis (M. En.)--Miami University, Institute of Environmental Sciences, 2004. / Title from first page of PDF document. Includes bibliographical references (p. 31).

Dissertation (PhD)--University of Stellenbosch, 2000. / ENGLISH ABSTRACT: The purpose of this dissertation is to provide methods for designing and managing low voltage residential feeders. These methods can be applied to the problem of planning residential networks under uncertainty while ensuring least life-cycle costs. By analysing collected load data from various communities in South Africa, a new probabilistic model for representing the load uncertainty of residential consumers was derived. This model uses the beta probability distribution to describe individual consumer loads over a period of time. Methods for combining the loads in linear combinations were used to derive a new probabilistic voltage regulation calculation procedure. This new method is different from previously developed voltage calculation methods in that it can be used to estimate the probable voltage performance of a feeder over a period of time. A simplification of the method is proposed which allows it to be implemented in any commercial spreadsheet program. The new probabilistic load model was also applied to the problem of calculating resistive losses in residential low voltage feeders. A new probabilistic method was formulated and this method can be used to estimate the probable range of resistive loss in a feeder for a period of time. This method is simple enough to implement in a commercial spreadsheet program. Probabilistic information about network and load parameter uncertainty is seldom available and these uncertainties are best modelled using fuzzy numbers. The probabilistic calculation methods cannot represent these uncertainties and only after applying a fuzzy-probabilistic approach can both types of uncertainties be used. This is a significant enhancement to the current methods and ensures that the uncertainty about the calculated results is realistically represented. The specification of load parameters for the methods was significantly simplified following a regression analysis of collected load data from South African communities. By specifying the distribution of the consumption of individual consumers in a community, the other load parameters can be estimated using a set of fitted linear regression equations. This greatly reduces the burden of specifying the load parameters and makes it possible for the proposed calculation methods to be applied to the design of new feeders in practice. The distribution of the consumption of individual consumers can be specified using the average and the standard deviation of the consumptions of individual consumers. Accurate estimates of these parameters can be obtained from sales information and can be used to manage existing networks effectively. Using the sales information with the proposed methods enables more cost-effective upgrades of existing feeders low voltage feeders. The identification of potential problems in existing low voltage networks is also possible if the layout of the feeders in a community is known. The use of the proposed methods is illustrated in step-by-step fashion. Typical input parameters are used and all the required calculations with intermediate results are presented. / AFRIKAANSE OPSOMMING: Die doel van hierdie proefskrif is die daarstelling van residensiële laagspanningsnetwerk ontwerp- en bestuursmetodes. Hierdie metodes kan toegepas word vir die beplanning van residensiële laagspanningsnetwerke waar onsekerheid bestaan oor toekomstige kragverbruik en die spesifikasie van die netwerkparameters. Lasdata, wat versamel is in verskeie Suid Afrikaanse gemeenskappe, is geanaliseer en 'n nuwe probabilistiese modellering van die onsekerheid oor die kragverbruik van residensiële verbruikers is ontwikkel. Gebruik is gemaak van die beta waarskynlikheidsdightheidsfunksie om die tydsgebonde kragverbruik van die verbruikers voor te stel. 'n Nuwe probabilistiese spanningsvalberekeningsmetode is ontwikkel en die metode maak gebruik van liniêre kombinasies van die lasstrome van die verbruikers. Die verskil tussen hierdie metode en bestaande metodes is dat dit die tydsgebonde waarskynlikheid van die spanningsregulasie van 'n kabel kan bereken. 'n Vereenvoudiging van die metode is ook verkry en dit kan in enige kommersiële sigblad geïmplementeer word. Die probabilistiese lasstroommodel is ook gebruik om 'n nuwe probabilistiese energieverliesberekeningsmetode te ontwikkel. Hierdie metode kan gebruik word om die tydsgebonde waarskynlikhede van 'n reeks van moontlike energieverlieswaardes te bereken. Die metode is eenvoudig genoeg om in enige kommersiële sigblad te implementeer. Onsekerheid oor die spesifikasie van die parameters van die nuwe metodes asook die netwerkparameters kan nie met probabilistiese metodes voorgestel word nie, aangesien inligting oor die waarskynlikhede van parameters selde beskikbaar is. Hierdie onsekerhede kan beter voorgestel word deur die gebruik van sogenaamde "fuzzy"-metodes. Die voorgestelde probabilistiese metodes is aangepas om hierdie tipe onsekerhede ook in ag te neem. "Fuzzy-probabilistic" metodes is gebruik vir dié aanpassings en word beskou as 'n noemenswaardige verbetering van die metodes. Die verbeterde metodes verkaf meer realistiese voorstellings van die onsekerheid oor berekende resultate. 'n Statisitiese analise van Suid Afrikaanse lasdata het 'n vereenvoudiging van die spesifisering van die parameters van die nuwe metodes tot gevolg gehad. Die waarskynlikheidsverspreiding van die energieverbruik van huishoudelike verbruikers kan gebruik word om akkurate skattings van die ander parameters te verkry. Hierdie vereenvoudiging het tot gevolg dat die nuwe metodes vir praktiese netwerkontwerp gebruik kan word. Die waarskynlikheidsverpreiding van die energieverbruik van verbuikers is beskikbaar in die vorm van energieverkope en kan gebruik word vir die effektiewe bestuur en opgradering van bestaande netwerke. As die uitleg van die bestaande netwerke in 'n gemeenskap beskikbaar is, kan die inligting wat bevat is in die energieverkope gebruik word om probleme in bestaande netwerke te identifiseer. Al die voorgestelde metodes is stap vir stap uiteengesit met voorbeelde van al die berekeninge met tipiese waardes.

Thesis (PhD)--Stellenbosch University, 2001. / ENGLISH ABSTRACT: Accurate load models are required for the computation of load flows in MV distribution networks. Modem microprocessors in recent times enable researchers to sample and log domestic loads. The findings show that they are stochastic in nature and are best described by a beta probability distribution. . In rural areas two different load types may be present. Such loads are domestic and pump loads, the latter may be modelled as constant P - Q loads. An analytical tool for computing voltage regulation on MV distribution networks for rural areas feeding the mentioned loads is therefore required. The statistical evaluation of the consumer voltages requires a description of load currents at the time of the system maximum demand. To obtain overall consumer voltages at any specified risk for the two types of the loads, the principle of superposition is adopted. The present work deals with conventional 22kV three-phase distribution (te:. - te:.) connected networks as used by ESKOM, South Africa. As the result of the connected load, MV networks can experience poor voltage regulation. To solve the problem of voltage regulation, voltage regulators are employed. The voltage regulators considered are step-voltage regulators, capacitors and USE (Universal Semiconductor Electrification) devices. USE devices can compensate for the voltage drops of up to 35% along the MV distribution network, thus the criteria for the application of the USE devices is also investigated. The load currents are treated as signals when assessing the cost of distribution system over a period of time due to power losses. The individual load current signal is modelled by its mean and standard deviation. The analytical work for developing general expressions of the total real and total imaginary components of branch voltage drops and line power losses in single and three-phase networks without branches are presented. To deal with beta-distributed currents on MV distribution networks, new scaling factors are evaluated at each node. These new scaling factors are derived from the distribution transformer turns ratio and the deterministic component of the statistically distributed load currents treated as constant real power loads. In the case of an individual load current signal, the transformation ratio is evaluated from the distribution transformer turns ratio and the average value of the· signal treated as constant real power load. The evaluation of the consumer voltage percentile values can be accurately evaluated up to 35% voltage drop. This is possible by the application of the expanded Taylor series, using the first three terms. The coefficients of these three terms were obtained using a search engine imbedded in the probabilistic load flow. The general expressions for evaluating the overall consumer voltages due to statistical and non-statistical loads currents are also given. These non-statistical currents may be due to constant P - Q loads, line capacitance and the modeling of voltage regulators. The Newton-Raphson algorithm is applied to perform a deterministic load flow on singlephase networks. A backward and forward sweep algorithm is applied to perform a deterministic load flow on single and three-phase systems. A new procedure for modelling step-voltage regulators in three-phase (te:. - te:.) connected networks is outlined. Specifying a transformation ratio of 1.1 and 1.15 respectively, identifies the open-delta or closed-delta configuration for three-phase networks. The algorithms and the developed general expressions for single and three-phase networks without branches are presented in this work. A new algorithm is developed to enable the developed general expressions to be applied to practical MV distribution networks. The algorithms were tested for their accuracy by comparing the analytical results with Monte Carlo simulation and they compared well. An illustrative example to show the application of the present work on a practical MY distribution networks is presented. A criterion for the application of the USE devices is outlined. It is anticipated that, the work presented in this thesis will be invaluable to those involved in the design of MY distribution systems in developing countries. / AFRIKAANSE OPSOMMING: Akkurate lasrnodelle word benodig vir drywingsvloei analises in MV distribusiestelsels. As gevolg van nuwe digitale verwerkers is dit deesdae moontlik om huishoudelike laste te monitor. Die lasdata dui daarop dat laste stochasties is en kan met behulp van die Beta verdeling beskryf word. In landelike gebiede is daar twee tipes laste. Hulle is eendersyds huishoudelike laste en andersyds pomp-tipe laste wat as konstante P-Q laste beskou kan word. Dit is dus belangrik om toepaslike analitiese metodes te gebruik om die spanningsvalle by hierdie laste te bereken met inagname van die las-tipes. By die statistiese berekening van die verbruiker se spanning moet 'n statistiese model van die lasstroom verskaf word op die tydstip van maksimum aanvraag. Daarna moet die prinsiep van superposissie gebruik word om die spannings by verskeie nodes by 'n gespesifiseerde vertrouensinterval te bepaal. Hierdie proefskrif is gebaseer op konvensionele 22kV, drie fase distribusie (delta na delta) netwerke, soos deur Eskom, Suid Afrika gebruik. Hierdie stelsels ondervind dikwels nadelige spanningsvlakke en spanningsreëlaars word derhalwe aangewend. Hierdie reëlaars is gewoonlik van tap-tipe of daar kan ook gebruik gemaak word van kapasitore en ook elektroniese reëlaars soos die USE tipe toestelle. Laasgenoemde kan op LV vir spanningsvalle tot 35% kompenseer. In hierdie werk word die werkdrywing verliese in die geleiers bereken met behulp 'n seinmodel van die lasstrome. Die individuele lasstrome word by wyse van gemiddeldes en variasies beskryf. Om die algemene algoritmes vir die berekening van die reële en imaginêre spanningsvalle, asook die verliese in enkelfase en driefase stelsels daar te stel word aanvanklik gebruik gemaak van stelsels sonder vertakkings. Om die statistiese lasbeskrywing op die laagspanningskant na die MV vlak oor te dra word van nuwe skaalfaktore gebruik gemaak. Hierdie faktore word bereken op die basis van die transformator se verhouding en die deterministiese komponent van die statistiese verspreide lasstrome, as konstante reële drywingslaste beskou. Met die ontwikkelde metode kan die verbruiker se spanning by 'n gegewe vertrouensinterval akkuraat bereken word vir spanningsvalle tot 35%. Dit word moontlik gemaak deur die Taylor-reeks tot drie terme toe te pas. Daar moet egter gebruik gemaak word van toepaslike koëffisiënte wat bepaal word deur 'n geprogrammeerde soektog. 'n Algemene stel vergelykings om die spanning by enige verbruiker te bereken, ongeag die topologie van die netwerk, word ook gegee. Die Newton-Raphson metode word aangewend om die deterministiese drywingsvloei op enkelfase stelsels te bereken. A truwaartse-voorwaartse metode is gebruik om die drywingsvloei te bepaal vir driefase stelsels. 'n Nuwe prosedure is ontwikkel vir die modellering van die spanningsreëlaars in driefase, delta-delta netwerke. Deur gebruik te maak van 'n transformatorverhouding van 1.1 of 1.15 kan die oop-delta of toe-delta netwerke voorgestel word. 'n Nuwe algoritme is ontwikkelom multi-vertakkings in 'n netwerk te hanteer. Al die prosedures is deeglik met behulp van Monte Carlo simulasies getoets en die resultate is heel bevredigend. Om die metodes te illustreer word 'n gevallestudie ingesluit waar die metodes gebruik word om 'n netwerk te evalueer met en sonder die sogenaamde USE toestelle. Kriteria vir die aanwending van hierdie toerusting word voorgestel. Daar word verwag dat die werk soos in hierdie proefskrifuiteengesit is die ontwerp van MV distribusiestelsels, veral in ontwikkelende lande, heelwat sal verbeter.

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

A dissertation submitted to the Faculty of Engineering, University of the Witwatersrand, Johannesburg, in fulfilment of the requirements for the degree of Master of Science in Engineering. Johannesburg 1996 / The use of computer-based tools in the design of electrical distribution networks results in the cost effective production and implementation of designs. This is because they help automate time-consuming routine tasks and enable the optimisation of certain aspects of a network design. The production of a tool that performs an optimisation on the low voltage (LV) portion of a distribution network is discussed. It uses the influence that a network's topology has on its associated cost, by applying a search that modifies the topology to result in a minimum cost. The modification of the network's topology is achieved through changing junction positions to alternative locations. It operates on an entire radial LV network, and therefore considers the coupling between junctions in the same network. The user of the tool must specify the alternative locations for each junction in the network, as well as information about the network, such as cable lengths and cable types. The search algorithm is based on an adaptation of the branch and bound method, which is a reduced search algorithm. It has been chosen as opposed to an exhaustive search algorithm to reduce computational requirements. The tool Is most useful for optimising completely underground distribution systems. Test results revealed a 7% saving in the cost of cables for a specific case study. The software has been developed with the application of object-oriented analysis and design within an ISO 9001 accredited software development environment. iii / GR2017

A dissertation submitted to the Faculty of Engineering and the Built Environment, University of the Witwatersrand, in ful lment of the requirements for the degree of Master of Science in Engineering. Johannesburg, 2016 / This research investigates the power sharing between distributed energy resources with voltage and frequency droop control. A case study based on voltage sources in an islanded microgrid is set up in the laboratory, referred to as: The Example Microgrid. The Example Microgrid consists of two synchronous generators, active and reactive power loads. A simulation model is constructed based on the laboratory set-up, where componentwise and system-wise testing are completed. The simulation results are validated with the experimental set-up, and it is concluded that the model accurately represents the physical system under steady-state conditions. Further simulation studies on conventional droop controllers are conducted based on the Example Microgrid model. The results indicate that the use of conventional droop control is inappropriate for small, low-voltage islanded microgrids. As a possible application of this work, three variations of adapted droop controllers are simulated and their performance evaluated. It is found that with the adapted droop controllers, the power sharing error can be minimised / M T 2016

Thesis (M.Com. (Development Theory and Policy))--University of the Witwatersrand, Faculty of Commerce, Law and Management, School of Economic and Business Sciences, 2016. / The paper identifies that due to the historic evolution of the South African economy, particularly the emphasis placed on energy provision as a catalyst for successful mineral extraction; the seeds were sown for South Africa to be an industrial hub in transformer manufacturing. However, this opportunity has not been realised. Domestic transformer manufacturers have continued to lose market share both domestically and globally. The research identifies a lack of demand, locally, for domestically manufactured transformers as an inherent cause of the challenges faced by the local transformer industry. This lack of demand is also recognized as the reason constraining the potential growth of the industry. The paper identifies a virtuous cycle between capacity utilization and expansion, wherein; higher capacity utilization favourably influences price competitiveness, which increases market share and induces investment into additional capacity. As greater market share is 2 | P a g e attained due to price competitiveness, even higher capacity utilization is achieved; therefore further inducing investment on the expanded capacity and the cycle continues with further expansion. The paper investigates sectoral designation as an industrial policy instrument to achieve this model, that is; increase demand, capacity utilization and ultimately broaden the industrial base of transformer manufacturing. The paper advocates that, while growing in the export market is the ideal end point, the industry would grow its current production capacity threefold if it were provided the opportunity to fully satisfy domestic demand1. As a result, this should be the first market to conquer. It is also identified in the research that sectoral designation as a policy instrument is not without shortfalls, particularly given the unique characteristics inherent in the transformer industry. The paper concludes with policy recommendations to overcome the identified shortfalls and proposes a model for consideration. This dissertation is submitted for the completion of a Master of Commerce in Development Theory and Policy degree. I would like to express utmost gratitude to Dr Paul Jourdan for his supervision, guidance and valuable contribution in the preparation of this research report. / MT2017