Emergency Power Balance Control Based On Proactive Motor Operation Of Dfig-Based Wind Turbines For Sending Grid Stability

The transmission lines between the sending and receiving ends of an interconnected power grid may be tripped under severe disturbance or equipment failure. The tripping will result in a large power imbalance in the sending grid, thereby causing frequency instability and even collapse. The effect of existing emergency control methods based on synchronous generators, such as generator tripping control, is limited due to the lack of available tripped generators, high cost and long recovery time. The high penetration and flexible controllability provide wind farms with the potential to participate in system emergency control. To evacuate excess power from the tripping of transmission lines and improve frequency stability, an emergency power balance control method based on the doubly-fed induction generator (DFIG)-based wind turbine (DFWT) is proposed in this study. A novel idea of the motor operation of DFWT is presented and applied to the proposed method. To realise steady and adjustable power consumption of DFWT under motor operation, a rotor virtual resistor control and supplementary pitch control are introduced under safety constraints. The validity of the proposed method is verified by case studies on single DFWT and DFWT-based wind farms.