Perturbation Observer Based Multiloop Control for the DFIG-WT in Multimachine Power System

This paper presents a novel perturbation observer-based multiloop control method for the integrated control of the doubly-fed induction generator-based wind turbine (DFIG-WT) in a multimachine power system. The DFIG-WT is decoupled into four independent subsystems in accordance with four outputs. A perturbation state is introduced into each subsystem, and the optimal output feedback control of each subsystem is achieved with the estimate of perturbation obtained by a sliding-mode perturbation observer. Thus a four-loop perturbation observer-based control (POC) scheme is adopted to achieve the integrated control of the DFIG-WT. The design of the four-loop POC does not require any accurate system model, and it is robust to external disturbances and parameter variations. Meanwhile, the four-loop POC presents a fast tracking rate and shows the capability of damping the oscillations of output variables. Moreover, interactions between two DFIG-WT-based wind farms and their influence to the stability of power system are also investigated. Simulation studies reveal that superior integrated control of DFIG-WT can be achieved by the four-loop POC under various conditions compared with the conventional vector control scheme.