Comparative analysis of two kinds of subsynchronous oscillation of direct drive PMSG based wind farm dominated by inner current loop

Aiming at the subsynchronous oscillation problem of direct drive wind farm in low operating conditions, the eigenvalue analysis method and impedance analysis method are used to analyze two kinds of subsynchronous oscillation problems caused by different current loop parameters of direct drive wind turbine group dominated by current inner loop control. The results show that: for the first kind of subsynchronous oscillation, the dominant influencing factors are the power grid strength and the current inner loop control parameters; with the decrease of the power grid strength, the current inner loop control parameters decrease, weakening the system damping, and the oscillation frequency gradually decreases; for the second kind of subsynchronous oscillation, the dominant influencing factors arc the current inner loop control parameters, with the decrease of the power grid strength The damping of the system is weakened and the oscillation frequency increases slightly. In EMTDC/PSCAD, the time domain simulation model of direct drive wind turbine group connected to AC power grid is built, which verifies the correctness and effectiveness of the theoretical analysis.