The energy production future is dominated by renewable energy sources driven by global warming problems and aiming at the reduction of fossil fuel dependence. Wind energy is becoming competitive with fossil fuels considering its less price and less CO2 emission production. Wind turbines consist of different types, including Doubly Fed Induction Generator (DFIG) which is a variable speed wind turbine and operates at varying speeds corresponding to the varying wind speeds from the cut-in speed through the rated wind speed to the cut-out speed. In the case of grid failure, the network voltage drops; consequently, the rotor current and DC link voltage increase which leads to damage of the rotor windings and power electronics device. Some protections are applied to the machine in order to help the Low Voltage Ride-Through (LVRT) ability of the doubly fed induction generator. In this root, the crowbar protection circuit is used widely in wind power plants. However, crowbar protection should be sized carefully due to its effects on both DC link voltage and rotor currents. In this paper, a doubly fed induction generator with crowbar protection is studied and the optimum value for the crowbar protection is derived; then, a Simulink model of a doubly fed induction generator protected by a crowbar protection is developed and used to analyze the effect of crowbar protection value on the DC link voltage and rotor currents. The results show a significant improvement in the LVRT ability of the DFIG.
Low voltage ride-through capability enhancement of grid-connected permanent magnet synchronous generator driven directly by variable speed wind turbine: a review
