Dual-axis supplementary controllers for multi-machine power systems

The effect of an additional field winding on the quadrature axis of the rotor of a synchronous generator in suppressing undesirable sustained oscillations experienced in multimachine power system is investigated. A small-perturbation model for interconnected power systems with dually excited synchronous machines is developed. A two-level optimal control strategy incorporating controls both on the direct and quadrature axes field windings is developed. A 3-machine, 9-bus power system was selected for studying the dynamic behavior of multimachine systems when stabilizing signals both on the direct and quadrature axes of the various machines are used. From a number of case studies it has been observed that an appropriate additional control in the quadrature axis enhances the stability of the system substantially.<
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