A Novel Current Reference Transformation-Based Positive and Negative Sequence Rotor Current Control Method of DFIGs

Abstract

The existing rotor current control methods, despite achieving simultaneous control on the positive and negative sequence rotor currents for the doubly-fed induction generator (DFIG)-based wind turbine, are still facing challenges. Specifically, some works introduce the sequence current decomposition into the classical control structure, which can deteriorate the dynamic performance. While others with high-order regulator embedded into the classical control structure can increase the risk of instability. To this end, this paper proposes a novel current reference transformation-based positive and negative sequence rotor current control method. Firstly, the negative sequence response of the DFIG under the classical single dq-PI rotor current control method is studied, pointing out its satisfactory dynamic performance but poor steady-state performance. Based on which, a transformation formula for the negative sequence rotor current reference is analytically derived to compensate for the steady-state performance. The corresponding analysis indicates that negative sequence rotor current static errors from parameter deviations can be well limited. Comparative simulations illustrated an improved dynamic performance and stability of the DFIG rotor current control with the proposed method. The experimental test of a prototype DFIG system has also been conducted to verify the feasibility of the proposed method in practical implementation.