Low voltage ride-through control strategy of a large capacity DFIG with grid-side thyristor controlled voltage regulator

With the rapidly increasing capacity of grid-connected wind power and the development of offshore wind power, the operating characteristics of wind turbine during the fault have drawn more concern. This paper adopts a relatively simple method to achieve low voltage ride-through (LVRT) of doubly-fed induction generator (DFIG) based wind turbine. A thyristor controlled voltage regulator (TCVR) is installed in the low-voltage side of the wind farm substation. When voltage dip occurs, the grid-side voltage is reasonably compensated according to the degree it drops to improve the stator voltage of DFIG, thereby reducing the flux changes in amplitude, so that the rotor current is restricted under the limit and at the same time the over-voltage of DC bus during the fault is suppressed. A 5MW DFIG wind power system model with the proposed control strategy is established in PSCAD/EMTDC to simulate the operating characteristics of the wind turbine under severe symmetrical fault to verify the validity of the proposed method.