The study on an adaptive terminal sliding mode excitation control of the grid-connected doubly-fed wind generator

In view of the no-load grid-connection problems of the doubly-fed wind power induction generator(DFIG), this paper researches its excitation control strategies in detail and proposes an adaptive terminal sliding mode excitation control strategy of grid-connected DFIG based on the structure decentralized theory, and establishes the mathematical model of the DFIG excitation controller before and after the grid-connection. On the basis of the model, the adaptive terminal sliding mode controllers of the d axis and q axis excitation currents of the rotor are designed. The simulation results show that compared with the conventional control methods this new control method can not only make the d-axis current and the q-axis current of DIFG to the reference values in finite time, but also whether the upper bound of the system uncertainties are known, the controller can always remain robust to it. This method reduces the system chattering effectively and improved the no off-grid ability during the grid-voltage fluctuation, It has important actual significance and practical application value.