Integrated excitation and turbine control in a multimachine power system

The authors are concerned with modelling and optimal control studies, by computer simulation of a multimachine power system comprising three interconnected generator units. The most effective generating unit, for the application of control, is determined by using eigenvalue analysis. A multi-input/multi-output linear model of the system, as seen from this unit, is obtained by least-squares identification. On the basis of this model a multivariable controller is designed, by minimising a quadratic performance index using the dynamic programming procedure. This local controller employs output feedback, and provides integrated control of the exciter and turbine-valve inputs. Multivariable controllers are also designed and applied to the other generating units, to allow comparative system performance to be examined. System behaviour is assessed in relation to small and large-disturbance studies. Simulation results include responses to three-phase short circuits, and dynamic and transient stability boundaries