A rotor position estimation system for a wind turbine generator comprising a doubly-fed induction generator (DFIG) having sensors coupled thereto, said rotor position estimation system being configured to receive a plurality of stator voltage and stator current signals (728, 730) from sensors and rotor current signals (704, 706, 708) from sensors, said rotor position estimation system including logic for determining a rotor position ε and comprising: a function block for generating a rotor current vector from the rotor current signals (704, 706, 708) comprising a rotor current vector α-component i ra signal and an orthogonal rotor current vector b-component i rb signal, said rotor current vector α-component i rα signal and said orthogonal rotor current vector b-component i rb signal being related to a rotor two-phase coordinate system defined by rotor α-axis and rotor b-axis; a function block for generating a sinρ 2 signal and a cosρ 2 signal, wherein ρ 2 is the angle formed between the rotor current vector and the axis of the rotor current vector α-component i ra signal; a module for receiving a stator voltage vector signal and a stator current vector signal from sensors and a stator resistance signal, and generating stator flux vector signals (734, 736) therefrom; a function block configured to receive the stator flux vector signals (734, 736) and generate rotor current estimation signals i s rα and i s rβ related to a stator α-β coordinate system and dependent on stator leakage inductance L s, respective stator current feedback signals i sα fbk and i sβ fbk, and a main magnetizing inductance (L m); a function block configured to receive the rotor current estimation signals i s rα and i s rβ and to generate a sinρ 1 signal 746 = i s rβ / i r s and a cosρ 1 signal 748 = i r α s / i r s where i r s is the magnitude of the associated vector for i r s in a stationery frame of reference; a module configured to receive the sinρ 2 signal, the cosρ 2 signal, the sinρ 1 signal and the cosρ 1 signal, and to generate a sinε' signal and a cosε' signal from the received signals such that sinε' = sin(ρ1-ρ2) and cosε' = cos(ρ1-ρ2); and a phase-locked loop configured to receive the sinε' signal and the cosε' signal and to generate a rotor position signal indicative of the rotor position ε. a function block for generating a rotor current vector from the rotor current signals (704, 706, 708) comprising a rotor current vector α-component i ra signal and an orthogonal rotor current vector b-component i rb signal, said rotor current vector α-component i rα signal and said orthogonal rotor current vector b-component i rb signal being related to a rotor two-phase coordinate system defined by rotor α-axis and rotor b-axis; a function block for generating a sinρ 2 signal and a cosρ 2 signal, wherein ρ 2 is the angle formed between the rotor current vector and the axis of the rotor current vector α-component i ra signal; a module for receiving a stator voltage vector signal and a stator current vector signal from sensors and a stator resistance signal, and generating stator flux vector signals (734, 736) therefrom; a function block configured to receive the stator flux vector signals (734, 736) and generate rotor current estimation signals i s rα and i s rβ related to a stator α-β coordinate system and dependent on stator leakage inductance L s, respective stator current feedback signals i sα fbk and i sβ fbk, and a main magnetizing inductance (L m); a function block configured to receive the rotor current estimation signals i s rα and i s rβ and to generate a sinρ 1 signal 746 = i s rβ / i r s and a cosρ 1 signal 748 = i r α s / i r s where i r s is the magnitude of the associated vector for i r s in a stationery frame of reference; a module configured to receive the sinρ 2 signal, the cosρ 2 signal, the sinρ 1 signal and the cosρ 1 signal, and to generate a sinε' signal and a cosε' signal from the received signals such that sinε' = sin(ρ1-ρ2) and cosε' = cos(ρ1-ρ2); and a phase-locked loop configured to receive the sinε' signal and the cosε' signal and to generate a rotor position signal indicative of the rotor position ε.