An important issue in today's power system is the need to analyse and determine the adequacy of transmission capacity. There is a need for approaches to increase transmission system capacity without construction of new transmission facilities, all while assuring secure operation of the grid. New technologies can enhance efficiency and reliability, increase capacity utilization, enable more rapid response to contingencies, and increase flexibility in controlling power flows on transmission lines. Distributed Series Reactor (DSR) control is a new smart grid technology that can be applied to control flows in the transmission system. DSRs can be used to balance phase flows in a single line as well as to control the distribution of flow in parallel flow paths. This dissertation investigates the Design of Distributed Series Reactors (DSRs) on transmission lines and provide guidelines and considerations for their implementation in bulk power system transmission networks to control power flow to: increase the exisiting transmission capacity utilization, alleviate overloads due to load growth and contingencies, and mitigate the effects of unbalanced voltages, unbalanced transmission line impedances and unbalanced loads by balancing flows in the phases of an unbalanced line. This dissertation provides several DSR System Design aspects; for a single line by performing an experiment for EHV and high voltage three parallel transmission lines, and for lines within the boundaries of a power system by deployment of DSRs over the IEEE 39 bus system that is modified and modelled as a 3-phase unbalanced transmission model with 345 kV lines that accounts for tower geometry and as a balanced, 3-phase model that is derived from the unbalanced, 3-phase model, and finally for lines within a control area and a set of tie lines among control areas by deployment of DSRs over a real system control area and the tie lines connecting this area to other power pool areas. For all experiments and simulations in this dissertation lines are modelled as 3-phase lines. The DSR system design for Unbalanced vs. Balanced 3-phase systems (Unbalanced immittance, Unbalanced load) are examined. Also the Distributed vs. Lumped models for 3-phase systems are tested. Comparison between DSR system design and transposition for voltage balancing was performed. The effect of bundling the conductors for DSR system design was investiagted. In this dissertation an economic evaluation of DSR System Design for parallel lines and for the IEEE 39 bus three-phase unbalanced line model for N-1 criterion contingency with load growth is performed. The economic evaluation performed for the DSR system design of a power system versus new transmission line construction showed that DSRs can be cost effective in managing load increases from year to a year, and thus avoid larger investments in new line construction until load expectations are proven to be true. Thus, a major value of DSRs is handling load growth in the short term, delaying larger investments. Although many aspects of DSR control implementation have yet to be explored, this work has demonstrated the fundamental concept is sound and the economics are compelling. / Ph. D.

Distributed Series Reactors (DSRs) can be used to control power flow to more fully utilize the capacity of a transmission network, delaying investment in new transmission lines. In this study the IEEE 39 bus standard test system is modified to a 3-phase, unbalanced model consisting of 230 kV, 345 kV and 500 kV lines, where lines of different voltage run in parallel. This model is used to study load growth and the effect of adding DSRs to alleviate resulting overloads, and in particular to alleviate overloads on lines of different voltage running in parallel. The economic benefit of adding DSRs to the network is compared to the addition of new transmission lines in the network. In the second part of the work, the effect of unsymmetrical operation of DSRs on a single transmission line is studied and compared to the symmetrical operation of DSRs. It is found that the unsymmetrical operation of DSRs is more economical. Finally the unsymmetrical operation of DSRs to reduce voltage imbalance in the network is considered. / Master of Science

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Thesis (MScEng (Electrical and Electronic Engineering))--University of Stellenbosch, 2005. / Power system stability simulations are of growing importance for studying the operational integrity of modern power systems, especially in developing economies where generating and transmission capacity lead the demand by relatively small margins. The relevant model topologies, i.e. for synchronous generators, automatic voltage regulators (AVR) and governor control systems, and the simulation software tools are well established. The MATLAB® Power System Blockset provides engineers with a versatile power system stability simulation environment, particularly where the focus is on individual units or small systems. In comparison with dedicated power system simulation tools such as DIgSILENT®, the MATLAB® environment features a superior set of advanced data processing and data analysis features. This includes features such as optimisation and parameter estimation functions. The main aim of this project is to make use of the MATLAB® package in a bid to test an alternative platform with which to estimate the synchronous machine parameters. Conditioning of field data can delay the process considerably, thus the secondary task of this thesis is to solve this issue by ensuring that only one platform is needed for the entire process starting in the field and ending in the modelling and parameter estimation environment within MATLAB®. In closing, the following points summarise the essential aims of this project: • An application using MATLAB® Script must be created that is responsible for importing and processing the data, so it is suitable for analysis purposes. The processing could include cropping, scaling and filtering of data. • Once the data has been imported it must be used with appropriate models to estimate for machine parameters. This will require the use of the Power Systems Blockset. The actual estimation process also requires the creation of an effective cost function, thus a number of different scenarios will have to be investigated before a solution can be found.

This study focuses on the experiences of a group of educators engaged in a professional development program by distance education in Papua New Guinea. The participants in this study have been keeping professional journals, for periods of up to three years, about their experiences of distance education. Their discourses have been used to form a ‘connected group’ of research participants, who use an action framework to focus on problematic issues surrounding distance education in Papua New Guinea. It is a piece of research, framed by critical theory, and characterised by participation, collaboration, reflexivity, reciprocity and empowerment. The process of the study is based in dialogue, and takes the view that research is constituted of a transformative perspective, which alters the way research participants understand the multiple realities in which they live and work, arid ultimately results in improvements in their lived experiences. The nature of the methodology privileges Voice' and a discourse of difference from each participant which contributes to the problematic nature of the study. The study has concerned itself, increasingly, with issues of power and control in the research process, and this has resulted in significant changes in the research as participants have become more conscious of issues such as distance, dialogue and difference. The study has evolved over a period of time in significant ways, and evidence is available that teachers in Papua New Guinea, despite structural and pedagogical barriers, are critically reflective and are able to transform their practice in ways which are consistent with social, cultural and political contexts in which they live and work. A number of 'local1 theories about research and distance education in Papua New Guinea are developed by the participants as they become informed about issues during the research. The practice of distance education and professional development, at personal and institutional levels, undergoes reconstruction during the life of the research and the study 'signals' other ways in which distance education and professional development may be reconstructed in Papua New Guinea.

Optimal transmission switching (OTS) enables us to remove selected transmission lines from service as a cost reduction method. A mixed integer programming (MIP) model has been proposed to solve the OTS problem based on the direct current optimal power flow (DCOPF) approximation. Previous studies indicated computational issues regarding the OTS problem and the need for a more accurate model. In order to resolve computational issues, especially in large real systems, the MIP model has been followed by some heuristics to find good, near optimal, solutions in a reasonable time. The line removal recommendations based on DCOPF approximations may result in poor choices to remove from service. We assess the quality of line removal recommendations that rely on DCOPF-based heuristics, by estimating actual cost reduction with the exact alternating current optimal power flow (ACOPF) model, using the IEEE 118-bus test system. We also define an ACOPF-based line-ranking procedure and compare the quality of its recommendations to those of a previously published DCOPF-based procedure. For the 118-bus system, the DCOPF-based line ranking produces poor quality results, especially when demand and congestion are very high, while the ACOPF-based heuristic produces very good quality recommendations for line removals, at the expense of much longer computation times. There is a need for approximations to the ACOPF that are accurate enough to produce good results for OTS heuristics, but fast enough for practical use for OTS decisions.

How does a social welfare officer know when a parent with mental illness or behavioral symptoms is harmful to the children? As a social you are confronted with different ethical dilemmas on a daily basis. The social welfare officers have to follow their own authorities, laws, guidelines and regulations while at the same time do everything to satisfy their clients’ needs. This inconsistency can sometimes be difficult to handle. The purpose of this study was to gain knowledge and a better understanding of how social welfare officers handles their elbow room in the field of actions to support the children of parents with mental illness. We have conducted a qualitative study where we interviewed six social welfare officers using the “vinjett” method. All social welfare officers included in the study are working with children of parents with mental illness. By using Michael Lipsky’s theory of Street-Level Bureaucrats we intended to get an understanding of how social welfare officers would act in specific situations. Our study shows that social welfare officers’ first contact is with the parents for a judgment of their capacity as parents. The results shows that the social welfare officers, who we interviewed, felt that they had a wide elbow room with resources to determine and shape different actions for the children of parents with mental illness but at the same time they experienced different barriers which may limit the alternatives in their decision-making. The majority of the social welfare officers in our study felt that they were aware of the power and control they possesses, which also are defined in Lipsky’s theory.

This thesis addresses the problem of reactive power scheduling in a power system with several areas controlled by independent transmission system operators (TSOs). To design a fair method for optimizing the control settings in the interconnected multi-TSO system, two types of schemes are developed. First, a centralized multi-TSO optimization scheme is introduced, and it is shown that this scheme has some properties of fairness in the economic sense. Second, the problem is addressed through a decentralized optimization scheme with no information exchange between the TSOs. In this framework, each TSO assumes an external network equivalent in place of its neighboring TSOs and optimizes the objective function corresponding to its own control area regardless of the impact that its choice may have on the other TSOs. The thesis presents simulation results obtained with the IEEE 39 bus system and IEEE 118 bus systems partitioned between three TSOs. It also presents some results for a UCTE-like 4141 bus system with seven TSOs. The decentralized control scheme is applied to both time-invariant and time-varying power systems. Nearly optimal performance is obtained in those contexts.

<p>How does a social welfare officer know when a parent with mental illness or behavioral symptoms is harmful to the children? As a social you are confronted with different ethical dilemmas on a daily basis. The social welfare officers have to follow their own authorities, laws, guidelines and regulations while at the same time do everything to satisfy their clients’ needs. This inconsistency can sometimes be difficult to handle. The purpose of this study was to gain knowledge and a better understanding of how social welfare officers handles their elbow room in the field of actions to support the children of parents with mental illness. We have conducted a qualitative study where we interviewed six social welfare officers using the “vinjett” method. All social welfare officers included in the study are working with children of parents with mental illness. By using Michael Lipsky’s theory of Street-Level Bureaucrats we intended to get an understanding of how social welfare officers would act in specific situations. Our study shows that social welfare officers’ first contact is with the parents for a judgment of their capacity as parents. The results shows that the social welfare officers, who we interviewed, felt that they had a wide elbow room with resources to determine and shape different actions for the children of parents with mental illness but at the same time they experienced different barriers which may limit the alternatives in their decision-making. The majority of the social welfare officers in our study felt that they were aware of the power and control they possesses, which also are defined in Lipsky’s theory.</p>

Thesis (Ph.D)--Electrical and Computer Engineering, Georgia Institute of Technology, 2009. / Committee Chair: Ronald G. Harley; Committee Member: David G. Taylor; Committee Member: Deepakraj M. Divan; Committee Member: Ganesh Kumar Venayagamoorthy; Committee Member: Thomas G. Habetler. Part of the SMARTech Electronic Thesis and Dissertation Collection.