Abstract: To the end of providing a constant AC voltage to a variable load (1) which is arranged remote of a voltage source (3), a voltage drop over an electrical supply line (2) which connects the load to the voltage source (3) is compensated for by a compensation AC voltage which, if added to the constant AC voltage, results into the output AC voltage Ufull of the voltage source (3) and the value of which is varied depending on the absolute value of the alternating current (I) conducted to the load (1) and on the phase angle phi between the output AC voltage Ufull of the voltage source (3) and the alternating current (I).

Abstract: A wind power station comprises a wind rotor; a transmission mechanically coupled to the wind rotor; an asynchronous generator having a generator rotor mechanically coupled to the transmission, and a generator stator electrically coupled to a power grid; and a protection unit protecting the generator and the transmission against accidental breakdowns of an alternating voltage provided by the power grid. The Protection unit includes at least one choke electrically arranged between the power grid and the generator stator, and a synchronous electrical machine electrically coupled to the choke.

Abstract: To the end of providing a constant AC voltage to a variable load (1) which is arranged remote of a voltage source (3), a voltage drop over an electrical supply line (2) which connects the load to the voltage source (3) is compensated for by a compensation AC voltage which, if added to the constant AC voltage, results into the output AC voltage Ufull of the voltage source (3) and the value of which is varied depending on the absolute value of the alternating current (I) conducted to the load (1) and on the phase angle phi between the output AC voltage Ufull of the voltage source (3) and the alternating current (I).