Abstract: A method for controlling the reactive power exchange of a DFIG wind facility with the grid is provided. The method includes determining a grid side converter reactive power thermal limit value and determining the value of the required DFIG magnetizing reactive power to be consumed by the stator. Then setting dynamically the sharing of the reactive power between the stator and the GSC such that the GSC reactive power value is the difference between the reactive power demand of the DFIG wind facility and the magnetizing reactive power consumed by the stator. Afterwards operating the DFIG wind turbine facility such that the absolute value of GSC reactive power is adjusted to be below the grid side converter reactive power thermal limit value value. An arrangement and a wind turbine are also provided.

Abstract: A method of controlling the operation of a doubly fed induction machine is provided. The DFIM includes a stator electrically coupled to a power grid and a rotor rotating with a rotational speed. The DFIM has a synchronous rotational speed of the rotor and a rated rotational speed of the rotor. Rotation of the rotor at the synchronous rotational speed generates one or more slot harmonic distortions having a harmonic order. The method comprises operating the DFIM at the rated rotational speed of the rotor, wherein the rated rotational speed of the rotor is set to a value selected such that a shift of the harmonic order of one or more of the slot harmonic distortions at the rated rotational speed of the rotor is an integer number or is within a predefined limit of an integer number.

Abstract: A method for controlling the reactive power exchange of a DFIG wind facility with the grid is provided. The method includes determining a grid side converter reactive power thermal limit value and determining the value of the required DFIG magnetizing reactive power to be consumed by the stator. Then setting dynamically the sharing of the reactive power between the stator and the GSC such that the GSC reactive power value is the difference between the reactive power demand of the DFIG wind facility and the magnetizing reactive power consumed by the stator. Afterwards operating the DFIG wind turbine facility such that the absolute value of GSC reactive power is adjusted to be below the grid side converter reactive power thermal limit value value. An arrangement and a wind turbine are also provided.

Abstract: A method of manufacturing a permanent magnet module for a permanent magnet machine includes the steps of: providing at least a permanent magnet, manufacturing a cover for covering the permanent magnet, the cover including a stainless steel, wherein the cover includes at least a top side and two lateral sides, the magnetic permeability of the top side being higher than the magnetic permeability of the lateral sides, the lateral sides being respectively attached to a first and a second edge of the top side, the lateral sides being angled with respect to the top side, attaching the cover to the permanent magnet.