Nonlinear Adaptive Control of Doubly-fed Induction Generator for Variable Speed Wind Turbine

Doubly-fed induction generator wind turbines (DFIG-WTs) have been widely adopted by the current wind power generation systems (WPGSs) due to their cost-effective provision of a high efficiency energy conversion via variable speed operation. Most of the installed DFIG-WTs utilise vector control (VC) for the power control of DFIG. To cope with the increasing demand of integrating the large capacity of wind power into the current power grid, grid operators require that the WPGSs should ride through grid faults and support grid stability. However, VCs are not capable of providing satisfied fault ride-through capability as they are mainly derived based on the steady-state operation of the DFIG. On the other hand, the time-varying nonlinearities and disturbances existing in the DFIG-WTs are needed to be tackled so as to improve the energy conversion efficiency. This proposal will investigate an advanced nonlinear adaptive control algorithm for the DFIG-WT to improve the energy conversion efficiency, the fault-ride through capability and the support of grid stability. The proposed controller will adaptively compensate unknown and time-varying disturbances such as intermittent wind power inputs, the nonlinear dynamics of the DFIG-WT and the power grid. Without relying on an accurate system model, the developed controller will have a relative simpler control algorithm compared to other advanced control methods and can be implemented based on the current hardware used by the vector control method. Due to the wide usage of the DFIG-WTs in the current WPGSs and in the fast growing offshore wind farms, designing a novel controller and upgrading the current used VCs will have great practical importances and help the integration of large capacity of wind power into power grid.