An enhanced control scheme for unbalanced operation of doubly-fed induction generator

This paper presents a control strategy to enhance the capability of doubly-fed induction generator(DFIG) based system during grid voltage unbalance, in which the model of DFIG is derived and analyzed. Active power, reactive power and generator torque are also defined under these conditions, based on these analyses, the control targets of RSC are discussed and positive and negative components are controlled in positive and negative synchronous reference frame respectively. Traditionally, low pass or band stop filter is used to extract positive and negative component, but the intrinsic time delay may cause slow response speed and make the system unstable. Hence, a fast decomposition algorithm instead of using low pass or notch filter is used to decompose positive and negative sequence, in order to validate the proposed strategy, simulations have been carried out, the results demonstrate the effectiveness of the proposed strategy.