A nonlinear optimal control method for synchronization of distributed hydropower units

To ensure the quality of the electric power produced by renewable sources synchronization of distributed hydropower units is needed. To this end, a nonlinear optimal control approach is proposed for stabilization and synchronization of distributed hydropower generators. Through the use of first-order Taylor series expansion and the computation of the associated Jacobian matrices the dynamic model of the interacting hydropower generation unit undergoes approximate linearization. The linearization point is updated at each time-step of the control method. For the approximately linearized model of the distributed hydropower system an H-infinity feedback controller is designed. This controller achieves solution of the related optimal control problem under model uncertainty and external perturbations. For the computation of the controller's feedback gains an algebraic Riccati equation is repetitively solved at each iteration of the control algorithm. The global asymptotic stability properties of the control method can be proven through Lyapunov analysis. Finally, to achieve state estimation-based control for the system of the distributed hydropower generators the H-infinity Kalman Filter is used as a robust state estimator.