Abstract: Some general aspects of the invention provide a method for operating a wind energy converter having a variable-ratio gear system mechanically coupled between a rotor and a generator, wherein the variable-ratio gear system includes a first hydraulic unit coupled to a first shaft and a second hydraulic unit coupled to a second shaft. The method comprises adjusting the variable-ratio gear system to a first gear ratio at which the first shaft substantially does not rotate; determining a wind speed or a related parameter (n, P, p); detecting whether the wind speed or the related parameter (n, P, p) has crossed a first threshold value in a first direction; and adjusting the variable-ratio gear system, when the wind speed or the related parameter (n, P, p) has crossed the first threshold value in the first direction, to a second gear ratio at which the second shaft substantially does not rotate.

Abstract: A wind energy converter configured for transmitting power to an electric grid includes a variable ratio gear system mechanically coupled between a rotor and a generator. A control system is configured to mechanically control a rotational speed of the generator so that, during a low voltage event, the wind energy converter can continue to operate and supply power to the grid.

Abstract: Some general aspects of the invention provide a method for operating a wind energy converter having a variable-ratio gear system (906, 172-178) mechanically coupled between a rotor (102) and a generator (104), wherein the variable-ratio gear system (906, 172-178) includes a first transmission unit (174) coupled to a first shaft (168) and a second transmission unit (172) coupled to a second shaft (165).

Abstract: A variable ratio gear system is configured for use with a constant speed generator being driven by a variable speed rotor. The variable ratio system includes three shafts: The first shaft is mechanically coupled to the rotor; the second shaft is mechanically coupled to a variable gear system; and the third shaft is mechanically coupled to the generator and the variable gear system. A control system is configured to adjust the output of the variable gear system to control the rotational speed of the generator. A brake is configured to control the rotation of the second shaft.

Abstract: A variable ratio gear system is configured for use with a constant speed generator (104) being driven by a variable speed rotor (102). The variable ratio system includes three shafts: The first shaft (144) is mechanically coupled to the rotor (102); the second shaft (160) is mechanically coupled to a variable gear system; and the third shaft (158) is mechanically coupled to the generator (104) and the variable gear system. A control system (109) is configured to adjust the output of the variable gear system to control the rotational speed of the generator (104). A brake (188) is configured to control the rotation of the second shaft (160).

Abstract: A wind energy converter configured for transmitting power to an electric grid includes a variable ratio gear system mechanically coupled between a rotor and a generator. A control system is configured to mechanically control a rotational speed of the generator so that, during a low voltage event, the wind energy converter can continue to operate and supply power to the grid.