Wind-thermal power bundled system with HVDC external transmission technology has become an ideal solution for long-distance transmission. To suppress the multi-modal sub-synchronous oscillation problem generated by the wind-thermal power bundled system

a suppression method based on the STATCOM/BESS is proposed. Firstly

the mechanism of STATCOM/BESS for suppressing SSO is analyzed. Secondly

based on wide area measurement system（wide area measurement system

WAMS）

the STATCOM/BESS suppression method for the SSO of the wind-thermal power bundled transmission system is designed

adding damping control to suppress multi-mode oscillation on the STATCOM/BESS current inner loop control loop

and the parameters of the controller are coordinated and optimized using the improved particle swarm algorithm for additional damping. Finally

on the basis of PSCAD/EMTDC platform

the simulation model of the wind-fighting baling system with STATCOM/BESS access is established. The effectiveness of the proposed suppression method is verified by simulation. It is shown by the result that the suppression strategy can effectively suppress SSO of the DC delivery system and improve the operational stability of the system.