AN OPTIMAL MULTIVARIABLE STABILIZER FOR A MULTIMACHINE PLANT

Abstract

In recent years, intermachine oscillations in a multimachine plant have received particular attention from power system engineers due to the undesirable effects of these oscillations on the system, and also due to the fact that the individual stabilizers now in use are not effective in damping out all modes of oscillation. A multivariable stabilizer may be advantageous to stabilize a multimachine plant in which all parallel connected units in the plant are acted upon at the same time. In this thesis, an optimal multivariable stabilizer is proposed based on the Generalized Heffron-Phillips model of a multimachine plant and on linear optimal control theory. The feedback function of the stabilizer is determined by minimizing a given quadratic cost function subject to the system dynamic constraints. The effect of different weighting matrices (0) on the system performance is discussed. Nonlinear simulation results for different disturbance cases are reported to demonstrate the great capability of such a controller to damp out the intermachine oscillations.