Abstract:To solve the high performance control grid-connected control problem of doubly fed induction generator(DFIG), we propose a predictive virtual torque control method for distributed DFIG grid connected inverter system. Virtual torque is derived from the concept of direct torque control in motor driven system. It is synthesized from the rotor flux of DFIG and the virtual flux of grid. On the basis of establishing the mathematical model of the DFIG grid-connected inverter system. The effects of voltage vectors in different sectors on virtual torque and rotor flux are analyzed. Sequence of three vectors containing two effective voltage vectors and a zero voltage vector are selected, and it also give a method to calculate the vector action time to make the power tracking. Finally, the performance of the proposed method is verified based on the 55 kW DFIG experimental prototype. The experimental results show that this method can achieve the DFIG system smooth and shock free grid-connection, and guarantee the dynamic and steady power quality of the grid-connection point.