Application of dynamic optimisation to synchronous-generator excitation controllers

Beginning with the equations in the electrical axes of a synchronous generator in the form v = Lpi + G¿ri + Ri, plant models are developed in a form that is particularly suitable for use in optimal-control-systems studies as applied to turbogenerator units. Algebraic state-variable transformations and a form of modal elimination are given in providing means of reflecting into formal optimising methods generator variables selected from considerations of the derivation of control signals from them. From this basis, a control strategy is derived using the matrix Riccati algorithm, and the fault-recovery response of a synchronous generator incorporating the strategy in its excitation controller is investigated. In computer-simulation studies, comparisons are made between the response of a strategy of the kind now in wide practical application, on the one hand, and the formally derived strategy, on the other. To provide means of validating much of the detail of plant modelling, the simulation studies correspond, as far as is possible, to plant and to controlled-fault conditions, for which site-test results are available.