Effectiveness of B2BC-based SGSC–PGSC and NSC-based SGSC–PGSC in a DFIG-based Grid-connected WT System – A Comparative Study

Abstract

ABSTRACT This paper presents the doubly fed induction generator (DFIG)-based wind turbine (WT) system with a back-to-back converter (B2BC) and nine-switch converter (NSC) as well as their control schemes. A new slip speed estimator-based control method is also proposed to control RSC of the DFIG-WT system. The system responses are obtained using two different converter topologies, namely (i) B2BC and (ii) NSC-based series grid-side converter (SGSC)–parallel grid-side converter (PGSC) under unbalanced/balanced grid disturbances due to balanced/unbalanced non-linear loads. Their responses are also compared to study the effectiveness of both the converter topologies. Moreover, the system responses are also obtained with the proposed slip speed estimator-based control scheme under varying wind velocity and compared with that of obtained using one of the existing control schemes. The system is modeled in MATLAB/Simulink platform. The time-domain simulation results are presented and analyzed in details. Results show that the B2BC- used with DFIG-WT system can be replaced by NSC under any loading condition and also the proposed slip speed estimator can offer good performance under varying wind velocity.