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[No abstract available] / Applied Science, Faculty of / Electrical and Computer Engineering, Department of / Graduate

In this thesis, resynchronization of a synchronous machine from a slipping state is considered. A set of equations for the slipping machine are developed. Slip tests on a dynamic test model are done to compare with computed results. A critical damping necessary for resynchronization is investigated, and an expression is derived. Tests are again carried out on a power system set up on the dynamic test model to verify the result. Finally, a nonlinear optimal control is developed and implemented on the test model. / Applied Science, Faculty of / Electrical and Computer Engineering, Department of / Graduate

In this dissertation a new model for the synchronous machine is presented. This model, based on non-standard test data, allows for the appropriate modelling of the frequency dependent behaviour of the damper windings. The non-standard test data consist of frequency responses, either measured or calculated. The form of these responses will automatically determine the order of the resulting model. Saturation effects in the synchronous machine are also modelled with this new method. The model was successfully tested in both an electromagnetic transients program (EMTP) and in a stability program. It was found that when frequency response measurements are used directly, the model is more accurate than when using the standard data from the manufacturer or data estimated to match approximately the frequency response measurements. It was also ascertained that this model could be used to speed up the solution in a stability program, both by allowing the user to match the order of the model to the required accuracy depending on the event and integration step, and by modifying the input frequency response data to minimize the discretization error made when using large integration steps. / Applied Science, Faculty of / Electrical and Computer Engineering, Department of / Graduate

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Deregulation of the electric utility industry has increased the need to monitor the state of powerplant equipment, such as critical generators and motors, to improve availability and reduce life cycle costs via condition-based maintenance. To achieve these goals, nondestructive condition assessment and diagnostic tests are necessary to evaluate the quality and condition of a machine?s stator winding insulation system. Periodic tests are generally conducted to monitor insulation aging, diagnose problems, or provide some assurance that the winding has a minimum level of electrical strength. The basic principles of insulation testing are presented herein, and the physical mechanisms that affect the current versus voltage response are described. A stator winding insulation model was developed based on this theoretical foundation for use in understanding and analyzing the macroscopic behavior of complex insulation phenomena. A comprehensive, controlled laboratory experiment was conducted on a set of stator coils that were deliberately manufactured with and without insulation defects. Specific defects were chosen to represent the types of insulation problems typically encountered during manufacture or as a result of in-service aging, and included lack of resin cure, loosely-applied insulating tapes, internal conductive contamination, reduced density of the groundwall insulation, and thermal cycling damage. Results are presented from a series of electrical tests conducted on the coil specimens to compare the effectiveness of various test methods in detecting the different insulation problems. The tests included insulation resistance, polarization index, ramped direct voltage, dissipation factor, dielectric spectroscopy, partial discharge, and recovery voltage measurements. Dielectric principles and testing experience obtained during this investigation were applied to a collection of test results obtained by the author from in-service machines during the past ten years. These results and analyses provide a practical illustration of the ability of the ramped direct high-voltage test method to distinguish between normal insulation and that with problems, and to help identify the cause and extent of the deficiencies. While no single diagnostic method is ideally suited to detect all possible stator winding insulation problems, ramped voltage tests are shown to be useful in determining when corrective actions are needed and what the appropriate actions are.

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