Analytical LVRT analysis of doubly fed induction generator with MPC‐basedDSCC/DRCC

Abstract

Under the low-voltage ride-through (LVRT) of the doubly fed induction generator, extra efforts are required for the model predictive control (MPC)-based direct stator/rotor current controls (DSCC/DRCC) against the stator flux oscillation. Constant stator/rotor currents are maintained at the cost of rotor/stator current oscillations, respectively, due to stator flux oscillation. Necessity to incorporate the stator flux transient in the MPC-based DSCC/DRCC under the LVRT is analysed based on tracking effects of the current references. To quantify LVRT effect with the MPC-based DSCC/DRCC, analytical expressions of the stator current, rotor current and rotor voltage are proposed, whose accuracy is validated based on comparison with the time-domain simulations. On the basis of analytical study, advantages and disadvantages of the DSCC/DRCC are analysed considering impacts of the current oscillations on the security of the rotor-side converter. With the DRCC, rotor voltage increase is suppressed with damping to the stator flux oscillation and rotor current constraint is satisfied without decreasing stator output power; thus, the LVRT effect is desirable compared with the DSCC. The MPC-based DSCC/DRCC is extended to LVRT under the asymmetrical fault to realise effective control to both the positive and negative sequence stator/rotor currents.