Optimal output feedback control of power systems with high-speed excitation systems

A method of designing a linear, optimal, constant, feedback control system based on quantities easily measurable at the synchronous generator location is presented for power system equipped with fast-acting excitation systems. The method is applied to a single-machine infinite-bus system, and the performance of the system to large disturbances, created by applying three phase faults, is studied. To permit meaningful comparisons between the proposed control scheme and conventionally used schemes, the performance of an ´optimized´ supplementary excitation control system is used as a base against which to judge the relative merits of the new scheme. It is found that the proposed control system design, when evaluated over a wide operating range, consistently results in improvements in system behaviour as compared to the conventional control system. To improve system reliability, the optimal control system design is carried out without assuming that the supplementary stabilizer is disconnected. Thus if, for any reason, the new control is not available, the system still has the benefit of stabilizing action provided by the supplementary stabilizer.