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La coopération politique bilatérale entre le Canada et les États-Unis dans le secteur énergétique : l'harmonisation des normes de fiabilité reliées au transport de l'électricitéLemieux, Christine. January 2007 (has links)
No description available.
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Particle contamination of high voltage DC insulators.Horenstein, Mark Nathan January 1978 (has links)
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.
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Impacts of automated residential energy management technology on primary energy source utilizationRoe, Curtis Aaron 08 November 2012 (has links)
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.
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Report of an internship with the Bureau of Land Management for the Falcon to Gonder construction projectBailey, Kenneth D. January 2004 (has links)
Thesis (M. En.)--Miami University, Institute of Environmental Sciences, 2004. / Title from first page of PDF document. Includes bibliographical references (p. 31).
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The analysis and quantifiaction of uncertainty for least life-cost electrical low voltage distribution designHeunis, Schalk W. (Schalk Willem) 12 1900 (has links)
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.
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Probabilistic analytical methods for evaluating MV distribution networks including voltage regulating devicesKundy, Beda Jerome 12 1900 (has links)
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.
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Transmission expansion planning in a restructured electricity marketLee, Cheuk-wing., 李卓穎. January 2007 (has links)
published_or_final_version / abstract / Electrical and Electronic Engineering / Master / Master of Philosophy
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The production of software that aids in the design of low voltage distribution networks by optimising the locations of junctionsApostolellis, Justin January 1996 (has links)
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
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Investigation into the steady-state load sharing of weak sources in a low voltage three-phase islanded microgridWu, Meng-Chun Merelda January 2016 (has links)
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
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An investigation into sector designation, prescribed in the Preferential Procurement Policy Framework Act (PPPFA), as a policy instrument for broadening the transformer industry's industrial baseChibanguza, Tafadzwa C January 2016 (has links)
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
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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
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