A METHOD FOR OPERATING A POWER SUPPLY SYSTEM AND A POWER SUPPLY SYSTEM

A method for operating a power supply system connected to a grid and including a rotor (106), a DFIG (118), a power conversion assembly (210), and an active filter (270) is disclosed. The DFIG (118) includes a generator rotor (122) mechanically connected with the rotor (106) and a generator stator (120). The power conversion assembly (210) includes a rotor-side power converter (220). The active filter (270) is electrically connected with the generator stator (120) via a stator bus (208). The rotor-side power converter (220) is electrically connected with the generator rotor (122) via a rotor bus (212). The method includes: determining (1100, 2100, 3100), based on a rotor frequency (fr) of the generator rotor (122), an expected harmonic frequency ({fh}) for a stator current (Is) flowing on the stator bus (208); determining (1200, 2200, 3200), in a data set comprising stator current values ({Is}), a current amplitude ({Ih}) of the stator current (Is) at the expected harmonic frequency ({fh}); and controlling (1300, 2300, 3300), based on the current amplitude ({Ih}) of the stator current (Is) at the expected harmonic frequency ({fh}), the active filter (270).