Integrated stability controller for VSCF wind generator

This paper presents a novel integrated stability controller for grid connecting variable-speed variable-pitch wind generator which regards the wind power system stability improvement and negative effect of stability control on wind generator reduction by wind generator power and pitch regulation. According to the full-state or non full-state nonlinear feedback strategy, the controller, which would `absorb´ system unbalance energy by wind generator power control, can improve the transient stability of the synchronous machine subsystem base on wide-area information. With the different correlation between wind generator and synchronous machines, the non full-state feedback strategy can relieve the control system communication burden greatly. According to the feed forward linearization H_∞ robust pitch regulation using extended state observer (ESO), the controller alleviates the extra mechanical loading from stability control on the drive-train by adjusting the aerodynamic torque. Simulation study implemented in Dig SILENT /Power Factory is conducted to demonstrate the effectiveness of the controller. The results show that, with integrated stability controller, the wind power system has less settling time, swing time, oscillatory peak value and more critical clear time; the wind generator has smaller torque fluctuation on drive-train and longer service life.