Nonlinear optimal control for hydro-power generation units

A nonlinear optimal (H-infinity) control method is proposed for the model of a hydro-turbine and synchronous generator power unit. At a first stage the hydropower unit un-dergoes approximate linearization around a temporary operating point which is updated at each iteration of the control method. To accomplish this linearization, the first-order Taylor series expansion of the dynamic model of the power unit is used and the Jacobian matrices of the state-space description of the system are computed. At a next stage, for the approximately linearized model of the power unit an H-infinity feedback controller is designed. The H-infinity controller stands for the solution of the optimal control problem of the system under modelling uncertainty and external perturbations. The controller 's feedback gains are computed through an algebraic Riccati equation which is repetitively solved at each iteration of the control algorithm. To prove the stability properties of the control scheme the Lyapunov method is used. The global asymptotic stability of the control loop is confirmed. Finally, for the implementation of state estimation-based control of the power unit, the H-infinity Kalman Filter is used as a robust state estimator.