Study on Suppression Strategy for Broadband Sub-Synchronous Oscillation in Doubly-Fed Wind Power Generation System

Abstract

In the power transmission of doubly-fed induction generators (DFIGs), sub-synchronous oscillation (SSO) can occur due to the influence of series compensation capacitance and long-distance transmission. SSO not only affects the output of the DFIG but also leads to oscillation diffusion. In order to solve the problem of disturbance in the control of the DFIG rotor side converter (RSC) under SSO, an adaptive quasi-resonant controller is proposed for the suppression of SSO. This strategy focuses on the propagation path of and frequency change in the SSO in the RSC control system and suppresses the SSO current in the wideband through the cooperative control of the back-stepping controller and the adaptive quasi-resonant controller. In this way, the stator-side output of the DFIG will not be affected by SSO, thus avoiding the amplification of the sub-synchronous power of the line by the DFIG. A simulation model and experimental platform were built to verify the suppression effect of this control strategy on the DFIG stator sub-synchronous current at different SSO frequencies. The results show that the proposed strategy has a good suppression effect on broadband SSO.

Keywords

• doubly-fed induction generator
• frequency of the sub-synchronous oscillation changes
• rotor side converter
• DFIG decoupling model
• back-stepping controller
• adaptive quasi-resonant controller