Abstract:Doubly fed induction generator (DFIG) is widely used in wind farms due to its advantages of variable speed and constant frequency.With a large number of wind power sources connected to the grid,the use of long-distance high-voltage transmission technology is likely to cause the risk of subsynchronous oscillation (SSO).The stator winding of DFIG is directly connected to the power grid,so it is very easily affected by the subsynchronous oscillation of the power grid in the operation process.This paper studies the subsynchronous oscillation and suppression strategy of DFIG.Firstly,this paper establishes the mathematical model of DFIG system,analyzes the control strategy of DFIG control system,then proposes an improved phase-locked control technique based on second-order generalized integrator (SOGI) for subsynchronous oscillation and compared with traditional phase-locked methods.Finally,a resonant control strategy is adopted in the rotor-side converter (RSC) to suppress the impact of subsynchronous oscillation on the stator output.The correctness and effectiveness of the control scheme is verified through Matlab/Simulink software simulation.