Control of a doubly-fed induction generator under grid faults using a d-q hysteresis current regulator

This paper investigates a control strategy for grid-connected wind energy conversion systems with doubly-fed induction generators, that employs a novel d-q hysteresis current regulator in the inner control loops. Although the current control is implemented in a rotating reference frame synchronous to the positive sequence space vector of the grid voltage, it can be used to generate negative sequence components which are useful in the presence of unbalanced conditions in the grid. The steady-state and dynamic performance of the control system is investigated under normal conditions as well as during abnormal conditions such as grid faults.