Transient response improvement of doubly-fed induction machine during unbalanced network

This paper proposes an integral control scheme for doubly-fed induction machine (DFIM) based wind generation system. A positive and negative dq sequence model is presented which is used to analyze the transient response under both balanced and unbalanced network disturbances. The integral control optimizes the input signals (machine and converter currents) to the reference values with full state feedback so that no vague controller parameter (such as PI controller parameters) is needed. The reference values are calculated from the control targets, i.e. constant power and results in no oscillation, limited overshooting, avoidance of overcurrent and so on. Algebraic Riccati Equation is introduced to give the solutions for the controller parameters. Experiment studies verify the effectiveness of the control strategy in improving the transient response for a DFIM system under unbalanced conditions.