Abstract: DC blocking can cause transient overvoltage in the wind-thermal-storage system with multi-channel delivery. Firstly, the paper analyzes the impact of the surplus reactive power and the strength of the sending-end system on the transient overvoltage of the AC system after blocking. Secondly, the paper analyzes the mechanism of various adjustment methods to deal with blocking faults, which include: the flow transfer of the remaining delivery channels except the blocking line, the regulation of pumped storage and power-type energy storage. And the action sequence is determined according to the characteristics of each method, and a coordinated stability control measure is proposed that comprehensively considers multiple adjustment methods. Finally, the Hami power grid model is built based on DIgSILENT for simulation verification. The simulation results show that coordinated multi-means stability control measure can effectively alleviate the transient overvoltage problem, reduce the number of machine cutting, avoid the cascading disconnection risk of wind turbines, reduce the control cost, and improve the coordination recovery ability of the AC system.

Key words: AC-DC hybrid connection, DC blocking, flow transferring, pumped storage, wind-thermal-storage hybrid system, stability control measure