Participation Factors Instability and Analysis of Direct-Drive Wind Farms with VSC-HVDC Systems

This paper reveals a new phenomenon that when there are close eigenvalues in direct-drive wind farms with VSC-HVDC systems, participation factors may change significantly under a small parameter perturbation. In light of this, the phenomenon is defined as participation factors instability, which is theoretically proved. Besides, as participation factors affect the optimal location of damping controllers, the participation factors sensitivities against key parameters are analyzed to guide the design of damping controllers. PSCAD/EMTDC simulations of a three-machine model are performed to verify the theoretical analysis.