Sensorless operation technique of doubly-fed induction generator connected to DC grid through two full controlled converters

In order to avoid the drawbacks of the position encoder in DFIG operation, this paper presents a sensorless operation technique when DFIG is connected to DC grid through two full controlled converters. The rotor position phase locked loop (PLL) is employed to estimate the rotor position and speed of DFIG based on the rotor current. The rotor position PLL is parameter insensitive, requiring only an estimation of the magnetization inductance for it to operate and the parameter sensitivity is also analysed. Simulations are conducted to validate the technique presented above.