A novel control strategy for the doubly fed induction generators to improve grid fault ride-through capability

An extended power angle concept based control scheme of doubly fed induction generators (DFIGs) is proposed to operate in place of the conventional PQdq control scheme during the grid fault ride-through (FRT) in this paper. In contrast to the PQdq control, the proposed control has a way better capability to support the terminal voltage of DFIG during the fault period, so that it can help DFIG ride through severe grid faults more efficaciously. The extended power angle of DFIG is defined firstly and then the mechanism of DFIG transient behaviors is revealed based on the understanding of the transient characteristics of the defined power angle. The new control solution of DFIG is designed and verified afterwards. In the paper, an example of 16-machine 5-area power system with 2 grid-connected DFIGs is presented to demonstrate the effectiveness of the proposed control strategy when applied in the large-scale power systems during the system disturbance. Simulation results show that both the capability of FRT of the DFIG and the transient stability of the whole power system are greatly enhanced by the application of this control scheme compared with the PQdq control method.