Suppression Method of Sub-/Super-synchronous Oscillation in D-PMSG Wind Farm Grid-connected Power Systems

Abstract

The sub-synchronous oscillations (SSO) caused by the grid integration of wind power have seriously threatened the safe and stable operation of the power system. Therefore, the suppression schemes of SSO have attracted extensive attention from the academic and industrial communities. However, the existing SSO suppression methods have the limitations of either changing dynamic performance of the direct drive permanent magnet synchronous generators (D-PMSG) wind farm, complex control schemes, or high control cost. To address these problems, a novel SSO suppression method based on the phase-locked loop (PLL) additional control is proposed in this paper. First, impedance sensitivity and the poles of the D-PMSG wind farm system are studied, the decrease of PLL’s bandwidth is found to be important and benefit to the grid-integrated stability. Secondly, a suppression scheme with additional damping at the PLL is proposed to indirectly reduce the bandwidth of the PLL once SSO occurs. Finally, the effectiveness of the proposed suppression method is verified in time-domain simulations that SSO converges only in 1 second.