Nonlinear, Optimal Control of a Wind Turbine Generator

In this paper, the design of a nonlinear rotor-side controller (RSC) is developed for a wind turbine generator based on nonlinear, H₂ optimal control theory. The objective is to demonstrate the synthesis of a maximum power point tracking (MPPT) algorithm. In the case of a doubly fed induction generator, it is essential that the RSC and the MPPT algorithm are synthesized concurrently as the nonlinear perturbation dynamics about an operating point is either only just stable or unstable in most real generators. The algorithm is validated based on using nonlinear estimation techniques and maximizing an estimate of the actual power transferred from the turbine to the generator. The MPPT algorithm is successfully demonstrated both in the case when no disturbances were present, as it is a prerequisite for successful implementation, and in cases when significant levels of wind disturbances are present.