Research report to School of Electrical and Information Engineering / An investigation was conducted into how a variable speed drive can provide a damping torque when mechanical oscillations are present. The modeling of mechanical oscillations via an analogous electrical circuit was performed. Simulation was used to demonstrate how a variable speed drive is able to damp speed oscillations using Direct Torque Control (DTC). Damping of mechanical oscillations is done by means of the variable speed drive providing a damping torque component that is in-phase with the speed deviation. The simulation showed that by applying a small torque component with the speed variation results in torque oscillations being damped by 60% after the initial disturbance. Damping is further improved by applying a torque component equal to the speed variation resulting in the oscillations being damped by 80% when compared to the initial disturbance. / MT2017

Present trends toward long distance extra high voltage transmission lines and static excitation can cause a reduction in the stability margins of a typical power system unless measures are taken to improve the system damping. Practical applications of stabilizing signals are investigated in this thesis and limitations of the design techniques discussed. An optimal control signal is derived from modern control theory. All signals are obtained from a common linearized power system and the performance is tested for large disturbance conditions on a single machine-infinite bus system where the machine, exciter and governor are represented in detail. Both types of signals are also tested on a practical four machine system model and it is shown that a similar improvement in damping can be obtained with either a stabilizing signal derived using conventional frequency response techniques or a proportional feedback controller obtained from solution of the algebraic matrix Riccati equation. / Applied Science, Faculty of / Electrical and Computer Engineering, Department of / Graduate

Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1981. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING. / Includes bibliographical references. / by Sherman Man Chan. / Ph.D.