Power Quality Improvement Through Backstepping Super-Twisting Control of a DFIG-Based Dual Rotor Wind Turbine System Under Grid Voltage Drop

The stator field-oriented control (SFOC) strategy, utilizing classical proportional-integral (PI) regulators for the doubly fed induction generator (DFIG) within a dual rotor wind turbine (DRWT) system, encounters several significant challenges. These challenges encompass undesirable fluctuations in stator active and reactive powers, the occurrence of a coupling effect in specific scenarios, and a lack of robustness. Moreover, the conventional SFOC demonstrates suboptimal performance in the presence of grid voltage drop scenarios. To address these issues, this study proposes the application of a backstepping super-twisting control (BSTC) strategy. The design of the controller involves integrating a super-twisting algorithm (STA) term into the control law of the classical backstepping control (BC) approach. The MATLAB simulation tests conducted on a 1500 KW DFIG-based DRWT system illustrate the clear superiority of the proposed BSTC over conventional SFOC, BC, and some previously published control methods. In the reference tracking test, the results indicate a significant reduction in the total harmonic distortion (THD) value of the stator current by 57.14% compared to SFOC and by 33.33% compared to BC. Additionally, the BSTC technique, in the same test, also reduces the steady-state error (SSE) for active power by 60% and 28.57% compared to SFOC and BC, respectively. Concerning reactive power, the proposed BSTC strategy decreases SSE by percentages estimated at 56.25% and 12.5%, respectively, compared to SFOC and BC. The computed percentages illustrate the substantial superiority of the suggested controller in enhancing power system characteristics and elevating the quality of energy.