Across many countries wind turbines generation systems (WTGS) have been installed over the past few years. However, the power generated is inconsistent due to wind speed variations. The power generated and the losses in wind turbine changes corresponding with change in wind speed. The only type of machine which can generate power at speeds below the fixed speed is Doubly Fed Induction Generator (DFIG). But DFIG is oversensitive to grid faults, which makes to fail the Bidirectional converters and dc link capacitor due to high inrush current and over voltage. Hence protection techniques are required to prevent DFIG from grid fault. In order to stay connected to the grid during voltage dip, low voltage ride through (LVRT) is an essential phenomenon. The above said problem is rectified by using eight protection techniques to prevent DFIG during voltage dip are implemented. These eight methods are Blade pitch angle control, DC Chopper, crowbar circuit, series dynamic resistance, Battery energy storage system, switch-type fault current limiter, Dynamic Voltage Restorer and FACTS Devices. The various hardware requirements and different control schemes are studied and discussed in this paper to enhance LVRT capability. Torque, speed and thermal stress are analyzed for symmetrical and unsymmetrical fault conditions.

Index Terms- Doubly-fed Induction Generator (DFIG), Low Voltage Ride Through (LVRT), Blade pitch angle control, Crowbar circuit, DC Chopper, series dynamic resistance (SDR), Battery energy storage system (BESS), Switch-Type Fault Current Limiter (STFCL), DVR , FACTS Devices