A Novel LVRT of Permanent Magnet Direct-Driven Wind Turbine

The low-voltage ride-through (LVRT) capability of a MW-Level variable speed wind turbine with a direct-driven permanent magnet synchronous generator (PMSG) is a hot topic these days. To prevent over-rated dc-link dynamic voltage, a novel dc-link voltage control scheme is proposed. In this paper comparing with traditional control method, the generator-side converter uses a doubly closed loop namely the inner stator current loop and the outer dc-link voltage loop. Grid-side converter also has dual-loop with inner grid current loop and outer generator speed loop, realizing maximum power point tracking. The simulation results confirm that the new control method can improve the low voltage ride through capability.