Thesis (M.S.)--Tennessee Technological University, 2009. / Title from title page screen (viewed on July 26, 2010). Includes bibliographical references.

Thesis (M.S.)--Oregon State University, 2010. / Printout. Includes bibliographical references (leaves 107-110). Also available on the World Wide Web.

Thesis (Dr.-Ing.)--Otto-von-Guericke-Universität Magdeburg, 2004. / "Untersuchungen zur Spannungsqualität in Verteilungsnetze under Verwendung der Spektralanalyse"--p. v. Includes bibliographical references (p. 114-123).

Thesis (M.S.) -- Worcester Polytechnic Institute. / Keywords: electric propulsion; applied magnetic fields; pulsed plasma thruster. Includes bibliographical references (p. 91-94).

Thesis (M.Sc.Eng.)-University of KwaZulu-Natal, Durban, 2008. / Full text also available online. Scroll down for electronic link.

Thesis (Ph.D.)--Washington State University, May 2006. / Includes bibliographical references (p. 102-106).

Thesis (Ph. D.)--Ohio State University, 2007. / Full text release at OhioLINK's ETD Center delayed at author's request

Thesis (Ph. D.)--University of Washington, 2006. / Vita. Includes bibliographical references (leaves 136-140).

Made available in DSpace on 2014-06-11T19:30:51Z (GMT). No. of bitstreams: 0 Previous issue date: 2012-04-05Bitstream added on 2014-06-13T20:21:18Z : No. of bitstreams: 1 moura_rf_dr_ilha.pdf: 1254278 bytes, checksum: 677c70fd86312d242054dec150169d11 (MD5) / Outros / Este trabalho trata da análise da estabilidade a pequenas perturbações de sistemas elétricos de potência multimáquinas considerando a atuação de Estabilizadores de Sistemas de Potência (ESPs) e de controladores do tipo Power Oscillation Damping acoplados a dispositivos FACTS UPFC (conjunto UPFC/POD). Um de seus objetivos é analisar como o posicionamento dos zeros da função de transferência em malha aberta (FTMA) do sistema elétrico de potência influencia na localização e na capacidade dos controladores em introduzir amortecimento às oscilações de baixa frequência. De maneira usual, uma análise de sensibilidade, através do método dos resíduos fornece a localização para instalação do conjunto UPFC/POD e/ou ESP. Entretanto, será mostrado neste trabalho que a quantidade de amortecimento fornecido ao modo eletromecânico de interesse utilizando os controladores suplementares de amortecimento é limitada pelo zero da FTMA do controlador. Desta forma, o ESP ou o conjunto UPFC/POD instalado na melhor localização obtida através do método dos resíduos pode não fornecer o coeficiente de amortecimento desejado ao polo de interesse. Outro objetivo é o ajuste dos parâmetros destes controladores e são utilizadas duas técnicas, sendo uma baseada na compensação de fase e chamada de método dos resíduos. Também é proposta outra forma de ajuste, fundamentada em algoritmos genéticos. Para a execução desses estudos o Modelo de Sensibilidade de Potência é utilizado para a representação do sistema elétrico de potência. Resultados são apresentados para dois sistemas teste: sistema simétrico com 4 geradores, 10 barras e 9 linhas de transmissão e o sistema New England com 10 geradores, 39 barras e 46 linhas de transmissão / This work deals with the small-signal stability analysis of multimachine power systems considering the Power System Stabilizers (PSS) and Power Oscillation Damping (POD) performance. POD is coupled to the FACTS (Flexible Alternating Current Transmission Systems) UPFC (Unified Power Flow Controller). An analysis of the open-loop transfer function (OLTF) zeros of the electric power systems is carried out aiming to verify the influence of the OLTF zeros placement on the controllers location and ability to introduce damping to low frequency oscillations. In the usual way, a sensitivity analysis, using the residue method, provides the UPFC/POD and/or PSS location. However, will be shown in this work that the damping provided to interest eigenvalue using a supplementary damping controller is limited by the OLTF zeros placement. Thus, the PSS or the UPFC/POD installed in the best location obtained by the residue method cannot provide the desired damping coefficient to the interest pole. Another objective of this work is to evalmate the performance of the controller parameters tuning. Two techniques are used with this objetive. One of then is based on phase compensation and called the residue method. The second one is based on genetic algorithm method. For the execution of these studies the Power Sensitivity Model (PSM) is used to represent the electric power system. Results are presented for two test systems: a test system with 4 generators, 10 buses and 9 transmission lines and the New England System that has 10 generators, 39 buses and 46 transmission lines

The generation, transmission and distribution of electricity underpins modern technology and constitutes a necessary element for our development and economic functionality. In the recent years, as a result of environmental concerns and technological advances, private and public investment have been steadily turning towards renewable sources of energy, resulting in a growing penetration of those in the power network. This poses additional challenges in the control of power networks, since renewable generation is in general intermittent, and a large penetration may cause frequent deviations between generation and demand, which can harm power quality and even cause blackouts. Load side participation in the power grid is considered by many a means to counterbalance intermittent generation, due to its ability to provide fast response at urgencies. Industrial loads as well as household appliances, may respond to frequency deviations by adjusting their demand in order to support the network. This is backed by the development of relevant sensing and computation technologies. The increasing numbers of local renewable sources of generation along the introduction of controllable loads dramatically increases the number of active elements in the power network, making traditionally implemented, centralised control dicult and costly. This demonstrates the need for the employment of highly distributed schemes in the control of generation and demand. Such schemes need to ensure the smooth and stable operation of the network. Furthermore, an issue of fairness among controllable loads needs to be considered, such that it is ensured that all loads share the burden to support the network evenly and with minimum disruption. We study the dynamic behaviour of power networks within the primary and secondary frequency control timeframes. Using tools from non-linear control and optimisation, we present methods to design distributed control schemes for generation and demand that guarantee stability and fairness in power allocation. Our analysis provides relaxed stability conditions in comparison with current literature and allows the inclusion of practically relevant classes of generation and demand dynamics that have not been considered within this setting, such as of higher order dynamics. Furthermore, fairness in the power allocation between loads is guaranteed by ensuring that the equilibria of the system are solutions to appropriately constructed optimisation problems. It is evident that a synchronising variable is required for optimality to be achieved and frequency is used as such in primary control schemes whereas for secondary frequency control a dierent synchronising variable is adopted. For the latter case, the requirements of the synchronising feedback scheme have been relaxed with the use of an appropriate observer, showing that stability and optimality guarantees are retained. The problem of secondary frequency regulation where ancillary services are provided from switching loads is also considered. Such loads switch on and off when some prescribed frequency threshold is reached in order to support the power network at urgencies. We show that the presence of switching loads does not compromise the stability of the power network and reduces the frequency overshoot, potentially saving the network from collapsing. Furthermore, we explain that when the on and o switching frequencies are equivalent, then arbitrarily fast switching phenomena might occur, something undesirable in practical implementations. As a solution to this problem, hysteresis schemes where the switch on and off frequencies differ are proposed and stability guarantees are provided within this setting.