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Robustness and stability of powersystem models using damping and synchronizing torquesJanuary 1981 (has links)
Sherman M. Chan, Michael Athans. / Bibliography: leaf 9. / Caption title. "August 15, 1981." / Supported by the U.S. Department of Energy, Division of Electric Energy Systems, under Contract DEAC0178RA03395

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Microprocessorbased fieldoriented control of a synchronous motor drive using a threephase solidstate sinusoidal current source韋盧溝, Wai, Lokau. January 1988 (has links)
published_or_final_version / Electrical Engineering / Master / Master of Philosophy

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Application of quantitative feedback theory to robust power system stabiliser design.Chetty, Paramasivan. January 2003 (has links)
This thesis aims to verify the use of quantitative feedback theory (QFT) as a viable tool for designing power system stabilisers (PSS) for a single machine infinite bus system.
The result of the QFT design is verified by simulation of the linear and nonlinear models representing the power system, and also by experimental procedures carried out in a laboratory. QFT falls into the classical control category, and is a frequency domain design method. It is an alternative to other design methods such as root locus and Hoo . The QFT design procedure can be extended to a multimachine system and QFT designs of MIMO systems has gained impetus. From theory, through simulation, and to the final laboratory testing on a single machine, infinite bus system, it will be shown that the application of QFT to robust PSS design does indeed work. QFT is a design method that allows the designer to choose a set of realistic
operating points and to produce a design that include those points. Other methods allow the designer to produce a design for single operating point, and one has no idea how the design performs at the other operating points. / Thesis (M.Sc.Eng.)University of Natal, Durban, 2003.

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Robust power system stabilizer design.Moodley, Devandren. January 2002 (has links)
This thesis investigates the design of damping controllers to alleviate the problem of
low frequency electromechanical oscillations in power systems. The operating point
and network parameters of power systems are continually changing, resulting in
changes in system dynamics. The conventional controller design methodology has
therefore come under increasing scrutiny for its lack of considerations for robustness.
The thesis first outlines the conventional design of a power system stabilizer (PSS) and
then applies two robust techniques (Hoo and Quantitative Feedback Theory, QFT) to the
design problem. The single machine infinite bus (SMIB) model is used to illustrate the
procedure for all three design techniques. The final design is undertaken to illustrate the
more important problem of robust multimachine PSS design using QFT. The design
requires linearised models of the multimachine system. A brief discussion is given on
how these can be obtained. An introduction to decentralized control design in QFT is
included to support the multimachine design.
Chapter three proceeds through the design steps required to generate a conventional
PSS. The technique is shown to be simple for a given set of operating conditions. The
controller is shown to be adequately robust over the given set of operating conditions
albeit not by design.
Chapter four introduces a design technique that directly addresses robustness issues
during the controller design. For a restricted range of operating conditions the designed
controller demonstrates the desired robustness and performance characteristics. The
inherent difficulties with Hoo in PSS design become more apparent as the operating
range is extended.
Chapter five introduces the second robust controller design technique. QFT is shown to
be more adept at dealing with increased operating ranges and changing specifications in the singlemachine infinitebus case. The controller is easy to generate and performs
well over the entire range of operating conditions. QFT is also applied to the controller
design for a fourmachine study system. The design is a marginally more complex than
in the single machine case but is still easily accomplished.
This thesis confirms previous attempts at solving the design problem using the methods
outlined above. The performance of all controllers is assessed for small and large
disturbances using nonlinear time domain simulations with models developed using
PSCAD/EMTDC and MATLAB. / Thesis (M.Sc.)University of Natal,Durban, 2002.

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The application of controllable inverterbased series compensation to power oscillation damping.Chonco, Nkosinathi Stanford. January 2000 (has links)
Poorly damped oscillations that occur between the generators in large interconnected
power systems often limit the amount of power that can be transmitted through a
transmission corridor and are a threat to secure system operation. Coordinated
insertion and removal of capacitors in series with a transmission line is one of the
approaches that has been known for many years to be capable of enhancing the
damping of power system oscillations. Unfortunately however, this approach
historically relied on the operation of mechanical circuit breakers which were too
slow and unreliable for the highspeed and repetitive operation that such an
application demands. Recentlyemerged, highspeed powerelectronicbased
switching devices are finding increasing use in modem power systems in the socalled
Flexible AC Transmission Systems (F ACTS) concept. One particular FACTS
impedance controller, namely the inverterbased series compensator, can rapidly alter
the magnitude of capacitive compensating reactance in series with the line to make it
practically feasible to enhance the damping of power system oscillations via
dynamicallycontrolled series compensation.
This thesis identifies, in the literature, an insightful approach to the design of an
idealised controllable series compensator (CSC) damping scheme; such an approach
has been considered in the analyses of the thesis. Three mathematical models of a
singlemachine infinite bus (SMIB) system are developed and are subsequently used
in the initial design and analysis of a CSC damping controller carried out in the thesis.
The simple SMIB system case study is used to identify and investigate the factors that
have a significant impact on the performance of a CSC damping controller before
studying the more complex issue of interarea mode damping using a CSC.
This thesis successfully confirms the results of a previous analytical study in which an
idealised representation of the CSC was used, and extends the scope of that previous
study by also considering a detailed representation of one particular type of CSC: the
inverterbased series compensator. The two key findings of this extended
investigation are that the inverterbased form of controllable series compensator can
successfully be used to damp power oscillations and that, where the damping of oscillations is the particular focus of study, an idealised representation of the inverterbased
CSC is suitable for the analyses.
In the case of the interarea mode damping problem, the selection of an appropriate
input signal to the CSC damping controller is a key issue, since the oscillations that
are to be damped involve a number of participating generators. This thesis examines
the suitability of a few candidate input signals that have been proposed in the
literature using the conceptually simpler SMIB system analytical models that have
been developed. Finally, the thesis applies the understanding of CSC damping
controller design gained from the SMIB study to the problem of interarea mode
damping on a fourgenerator study system. Timedomain simulation results are
presented to demonstrate the impact of the controlled inverterbased series
compensator on the damping of the interarea mode of this system. / Thesis (M.Sc.Eng.)University of Natal, Durban, 2000.

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Voltage unbalance emition limits for new connections including single phase MV systems.Maloko, Thabane Silas. January 2011 (has links)
Voltage unbalance performance of a power line depends on a few parameters that are not necessarily constant at any given instance. The random nature of a power system raises questions around the ability of a system planner to allocate equitable share of the power quality parameters, like voltage unbalance, at design stage. Even a more interesting question is whether applying current methods will guarantee that emissions will be under the set limits. The presence of single or dual phase feeders on such a line will result in a more dynamic voltage unbalance.
The first part of this research is a study on deterministic method of voltage unbalance allocation presented by the IEC. The IEC 61000133 report is a comprehensive guideline and the best place to start when looking to develop an emissions standard for voltage unbalance. This dissertation presents a method that can be used to set planning levels for unbalance emission at various voltage levels in order to avoid high voltage unbalance at the end user. The method depends on the agreed power of the customer, the power of the unbalanced load, and the system characteristics. The method works well for short feeders with roughly the same negative sequence impedance and equal short circuit levels. In South Africa, however, there are radial feeders that span over 100km. Hence on such a feeder, there can be ratios of 1:10 between sending end and the last customer on the line. Preliminary research revealed that IEC 6100063, a report on allocation of harmonics, has a method applicable to long feeders. This method was investigated extensively and applied to voltage unbalance allocation. At the core of the method is the assumption that feeders have an even distribution of load. To illustrate the application of this method an example is given.
The second part of the study explores a stochastic method of voltage unbalance allocation. In this study the possibility of random connection is considered. A Monte Carlo study is presented. The impact of various parameters are analysed and the findings reveal that phase allocation has the most influence on emission. The results show that the method of random connection of loads can be applied in special conditions only i.e. were sizes of loads do not differ greatly and the number of required connections are low. / Thesis (M.Sc.Eng.)University of KwaZuluNatal, Durban, 2011.

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An expert system approach to voltage control design and operation in power systemsGodart, Thierry F. 08 1900 (has links)
No description available.

38 
Investigating the financial recovery of embedded generation in medium voltage distribution systems.Moonsamy, Raventhran. 29 October 2014 (has links)
Embedded generation (EG) provides many benefits in terms of reduction of system technical
losses and increased load carrying capacity. In this study the sustainable EG carrying capacity
permutations in a medium voltage distribution system, will be determined. Using these results,
the financial investment recovery potential of EG will be studied and the impact on the cost
recovery by the Utility as a result of compensating the EG at the current system marginal price,
will be analysed.
The study was done to show what capitalisation can be done on a medium voltage distribution
system, by the owners of EG plant receiving revenue from the Utility, at the system margin
price with the anticipated inflationary increases. The study will also cover the effect on the
revenue stream of the Utility as a result of voltage changes caused by the EGs to the loads being
supplied.
The electrical system used in the study consisted of a radial system with distributed load and
generation. The distributed loads were modelled using the average load capacity supplied by the
Utility in medium voltage system. The average volume of sales lost as a result of nontechnical
losses was included in the load model so that the overall accuracy of the revenue effect by EG
on the Utility, could be increased. The amount of capitalisation that is achievable by the owners
of the EG was tested against various practical permutation scenarios, including variation of
location, system impedance (different X/R ratios), time of operation and changing load volume
and type.
The extent of successful penetration of EG into the distribution system was found to be between
20% and 60% of the load carrying capacity of the system. The simulated results revealed
“bathtub curve” behaviour for the cost of energy losses and this reconciled with the theoretical
analysis of other studies done in this area. Lower volume penetration of EG results in higher
investment potential of up to ten million rand per MW with a 5% MARR per year. This is very
low when compared to the levelised cost of the expensive renewable energy technologies that
are currently available in the market. With higher penetration of EG on low impedance systems,
the gross contribution of the Utility is negatively affected which would introduce instability in
the SMP yearly increases. / M. Sc. Eng. University of KwaZuluNatal, Durban 2013.

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Design and coordination of stabilisers for generators and FACTS devices in multimachine power systems / by Pouyan Pourbeik.Pourbeik, Pouyan January 1997 (has links)
Bibliography: leaves 238248 / xxix, 248 leaves : ill. ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / This thesis is concerned with the design and coordination of linear, fixed parameter controllers for the purpose of enhancing the dynamic performance of a multimachine power system. The studies are based on linear control theory and involve state space analysis, modal analysis, eigenanalysis and conventional frequency response techniques. The emphasis is on the smallsignal performance of the system / Thesis (Ph.D.)University of Adelaide, Dept. of Electrical and Electronic Engineering, 1997?

40 
A control strategy for the power system of a hybrid vehicleFurrutter, Marco Klaus 24 October 2012 (has links)
M.Ing. / The increase in awareness of the environmental problems resulting from emissions released from vehicles have forced governments and car manufactures to invest more time in to the designing a vehicle that is an alternative to petrol driven vehicles. This dissertation aims to introduce a control strategy to manage the flow of energy of different power sources that may be found on a vehicle. Hybrid vehicles are a possible solution to reducing carbon emissions that play a part in global warming. In this dissertation, di erent hybrid vehicles are de ned and their components discussed in detail. The possibility of more than one energy source to power the vehicle introduces more exibility in terms of the drivetrain but this increases the complexity of the energy control management. The goal is to optimize the energy control management to reduce fuel consumption and therefore reduce emissions. Operating procedures for the various hybrid con gurations are discussed. Simulations of the Energy Management System of the hybrid electric vehicle are used to develop the control optimization algorithm. Various control optimization procedures are discussed. Satisfactory results from the simulations allow the implementation of the hybrid onto a platform entered into the South African Solar Challenge 2010, which covered a distance of 4000 km. The Energy Management system selected for the parallel hybrid electric vehicle demonstrated fuel savings, which meant a reduction in emissions, which is the goal of any hybrid vehicle. Further investigations include more intelligent controllers to adjust the parameters of the energy management controller to allow for adaptation to various driving conditions, e.g. urban and motorway driving.

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