Crowbar control algorithms for doubly fed induction generator during voltage dips

The paper presents different control strategies of the crowbar protection when a variable speed wind turbine based on a doubly fed induction machine is generating electrical energy during a voltage dip in the grid. The proposed control strategies provide the wind generator with the capacity for don´t disconnect from the grid while a voltage dip occurs, and return to the normal operation conditions. This is achieved by a protection circuit called crowbar. In addition, complementary control algorithms for flux damping and voltage recovery are proposed. Finally, the presented control strategies are validated in simulation for a 1700 KW generator