Output Feedback Event-triggered Control of Doubly Fed Induction Generators For Wind Turbines

We consider the problem of pitch angle control for doubly fed induction generators in wind turbines affected by external disturbances. We assume that only an output measurement is available and the feedback signal is transmitted over a digital channel to the controller. An event-triggered control algorithm is developed to produce the transmission instants of the output measurement. We follow the emulation approach in the sense that we first stabilize the plant in continuous-time where we synthesize a robust control methodology based on the Linear Quadratic Gaussian Regulator (LQG) approach. Then, we consider the effect of the network and we construct an event-triggering mechanism such that the closed-loop stability is preserved while the Zeno phenomenon is prevented by means of time regularization. The overall system is modelled as a hybrid dynamical system and the required stability conditions are formulated in terms of a linear matrix inequality. The effectiveness of the control method is illustrated by simulation on a numerical model of the DFIG wind turbine.