This dissertation addresses three different problems in power systems. The first problem is related to the fault location in complex topologies such as three terminal circuits with series compensation and mutually coupled line sections and distribution networks with distributed generation. Novel methods are presented by using traveling wave approach and wavelet transformation technique to overcome the difficulties introduced by the discontinuities and integrated components such as Metal Oxide Varistor (MOV) protected series capacitors and distributed generation in complex topologies. Simulation results show good correlation between the actual and estimated fault locations for all the studied cases. The second problem concerns the calculation techniques of voltage profiles along transmission lines. A simple yet effective approach to accurately and rapidly obtain the voltage profile along a transmission line during fault transients is presented. The objective of the presented method is to eliminate the need to use wave equations and line parameters provided that an electromagnetic Transients Program (EMTP) type transients simulator is available for generating bus voltage transients for a given fault. This is accomplished by developing a time series model to estimate the voltage at an intermediate point along the transmission line. The model is formed for each intermediate point separately. Once the model is obtained it can be used to predict the transient voltage at that point along the line during any fault in the system. The approach can potentially be useful as a post processor to a transient simulator and can be used by developers of transient animations and movies for illustrating fault-initiated propagation of traveling waves in power systems. The third problem is the lack of powerful visualization and animation methods, which can help understanding the complex behavior of power systems during transients. The goal of this part of the dissertation is to develop new animation and visualization methods for power system electromagnetic transients for both educational and research purposes. Proposed approaches are implemented in different environments such as MATLAB and Microsoft Visual Studio to show the effectiveness of two and three-dimensional visualization of power system transients. The implementations of the proposed methods provide better understanding of the power systems during transient phenomena due to the faults or switchings.

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This thesis describes the design of multivariable excitation controllers for synchronous generators, and their practical implementation on a laboratory machine system. The main objectives of the investigation were aimed at extending the steady-state stability limit of the generator and improving its general controllability. The present work is principally concerned with the implementation and test of the designs. Instrumentation has been developed to measure and combine feedback signals; this instrumentation and the laboratory generator system are described in detail. The performances of the controllers are predicted by computer simulation and evaluated by practical testing; attention is focussed on comparison of predicted and experimental performances. The theoretical basis of the design strategy is described, in which an optimal control algorithm applies the system states as feedback signals to the open-loop system, thereby shifting certain of the system eigenvalues to more desirable, predetermined locations. The state variables are selected as physically measurable quantities which obviates the need for implementing state estimation techniques.

In this thesis a robust nonlinear tracking is proposed for a class of single machine connected to an infinite bus (SMIB) systems. Designing of the controller is based on the backstepping control technique, where designer interlaces the choice of L yapunov functions in order to design the controller and analyze the stability of the power angle and rotating speed of the generator. Nonlinear models are considered directly in the designing process, hence neglecting the effects of nonlinear terms in the plant can be avoided, which may also improve the robustness of controlled system¡¦s transient stability. In order to enhance the applicability of the proposed control scheme, the perturbations that may encountered in the system are considered, and adaptive laws are embedded in the controllers so that the upper bound of perturbations need not to be known beforehand. Two numerical examples are given to illustrate the feasibility of the proposed control scheme.

This thesis designs a DSP-based controller which is composed of two parts,voltage controller and current controller.A proportional controller,treated as the current controller,is designed in the inner loop to control the capacitor charging current fast and effectively,especially when the sudden load is occurred.An PI controller,treated as the voltage controller,is designed in the outer loop to improve the system response irrespectively of system¡¦s parameter variation and load disturbance.The experimental result shows the output voltage can follow a sin wave which can match command exactly under the control scheme.

This paper investigates the concept of an isolated small wind power system based on a three-phase generator and a direct ac-to-ac conversion. The ac-to-ac conversion is performed by a matrix converter and thus removing the need of a large smoothing capacitor in the typical rectifier-inverter solution. The paper is briefly presenting the operation for a particular topology of a three-phase to single-phase matrix converter. The control of this conversion ensures system’s frequency and voltage stability. Simulation results and practical results are presented to validate the frequency and voltage regulation of the isolated power system.

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