Low voltage ride-through of directly driven wind turbine with permanent magnet synchronous generator

【Objective】 The control strategy for directly driven wind turbine with permanent magnet synchronous generator(D-PMSG) was investigated to enhance its capacity of low voltage ride through(LVRT).【Method】 A D-PMSG model comprising of a host AC power grid with two back-to-back PWM voltage source converters(VSCs) and a common DC link was established.The active and reactive powers of the two VSCs were independently controlled by the PI current controllers with feedforward decoupling.The real-time grid voltage was introduced into the reference power calculation of gen-side rectifier.The control strategy with reducing generator power based on the ratio of actual and rated grid voltage was proposed.【Result】 Simulation results showed that during voltage dip,the proposed strategy could limit both the DC voltage and inverter current.The rotational speed was limited at its reference by pitch angle controller.【Conclusion】 The power balance of generator and DC-link of the converters could be maintained through the employment of the proposed control strategy,thus the LVRT capacity of D-PMSG was enhanced,and the reactive power to the grid could also be supplied.