Fault ride through capability of double fed induction generator for wind energy system

Until recently it has been accepted that induction generator based wind turbines are disconnected from the power system in the event of a network disturbance. However, the increasing trend of connecting high penetrations of wind farms to transmission networks has resulted in the transmission system operators revising their grid codes for the connection of large MW capacity wind farms. The new grid codes require wind turbines to remain connected for a specified voltage disturbance on the network. Most of the wind generation plant being developed will use either fixed speed induction generator (FSIG) or doubly fed induction generator (DFIG) based wind turbines. The basics of using a doubly-fed induction generator (DFIG) to convert the mechanical energy of the wind into useful electrical power that can be used to supply electricity to any grid are presented. The ability of doubly fed induction generator based wind turbines to remain connected through power system disturbances is discussed. A crowbar protection system to provide a power system fault ride-through capability for doubly fed induction generator based wind turbines is also described. The dynamic behaviour ofDFIG wind turbines normal operation and during grid faults are simulated and assessed to verify the recommended method using a Matlab/Simulink developed model.