Research of generator-tripping strategy for wind-thermal-bundled power transmission system in emergency state

A catastrophic fault in the long-distance wind-thermal-bundled power transmission system (WTTS) would lead to transient angle instability and transmission line overload at the same time in the sending-end of WTTS. According to the traditional emergency control strategy, massive thermal power would be tripped, which is likely to reduce the damping ratio and increase the risk in transient recovery process. Therefore, considering three aspects simultaneously, transient angle instability, transmission line overload and low damping ratio, this paper proposes a coordination generator-tripping of synchronous generators and DFIGs control strategy. Based on the transient energy function method, a practical calculation method is proposed to calculate the least tripping value of synchronous generators. Then according to the overload value of transmission lines and the impact of DFIG penetration on damping ratio, the tripping value of DFIGs can be determined to meet the power system regulations. Finally, the validity of this strategy is verified by the simulation of the actual WTTS by PSD-BPA.