Dual-Mode Control for Brushless Doubly Fed Induction Generation System Based on Control-Winding-Current Orientation

Brushless doubly-fed induction generator (BDFIG) has huge potential due to its high reliability and low maintenance costs. In order to meet the requirements of the modern grid code, the BDFIG system should have dual-mode (i.e., operating in both stand-alone and grid-connected modes) capability. Rather than using two separated systems for two modes, this article proposes a unified control architecture for dual-mode operation. Such a unified architecture is based on the stand-alone control-winding (CW) current orientation, and the grid-connected functions are realized by adding three plug-in functional units: 1) the phase-lock function is realized by adding an increment adjustment controller into the CW-angle control; 2) the inrush current during mode switching is suppressed by adding a high-pass feedforward controller into the inner-loop controller; 3) the active power and reactive power are regulated by adding an amplitude-angle controller of CW current. With the proposed unified architecture, the high-performance dual-mode operation is achieved without breaking the original CW-current orientation system, facilitating the overall system design a lot. The detailed analysis and designs are given in this article, and the experiments based on a BDFIG prototype are given to verify the feasibility.