Analysis of Sub-synchronous Interaction Mechanism Between D-PMSG-based Wind Farm and LCC-HVDC

When the direct-drive permanent magnet synchronous generator (D-PMSG)-based wind farm is close to the rectifier station of line-commutated-converter based high voltage direct current (LCC-HVDC), sub-synchronous oscillation (SSO) is prone to occur, and existing research methods are difficult to analyze the internal sub-synchronous interactions of the system. In order to solve the above problems, this paper analyzes the sub-synchronous interaction between the D-PMSG-based wind farm and LCC-HVDC by studying the transfer path of sub-synchronous frequency disturbance. Firstly, the linearization model and closed-loop transfer function block diagram of the D-PMSG-based wind farm integrated with LCC-HVDC system are derived, and the damping torque analysis of the oscillation mode dominated by the DC inductor of LCC-HVDC is performed; then, the closed-loop transfer function block diagram is analyzed, and two disturbance transfer paths are obtained; finally, the damping reconstruction method is used to separate the damping of each path, the influence of damping of each path on SSO mode damping is analyzed, and the correctness of the damping reconstruction is verified by simulation.