Study on a coordinated SMC strategy for DC and doubly-controlled DFIG system

摘要

This paper proposed a coordinated sliding mode control (SMC) strategy for DC and doubly-controlled DFIG system to keep DFIG system from parameter perturbation and external disturbance in a DC grid. DFIG is connected to the DC grid by a rotor side converter (RSC) and a stator side converter (SSC), which overcomes the difficult connection DFIG with DC bus. However, this DC-based doubly controlled system structure increases its control difficulty. In this paper, three aspects are improved. First, RSC and SSC controllers are coordinated together to complete the power conversion targets. Second, rotor speed and torque SMC controllers are cascaded to make DFIG work at MPP mode. Third, flux SMC and reactive current SMC controllers confine their values to the target trajectories stably. Finally, simulations are carried out to verify the control strategy effectiveness.