Wind energy converter comprising a superposition gear

1. A method for operating a wind energy converter configured for transmitting power to an electric grid, the wind energy converter comprising a variable ratio gear system mechanically coupled between a rotor and a generator of the wind energy converter, the variable ratio gear system including at least one shaft coupled to the generator and a hydraulic circuit having

a hydraulic unit mechanically coupled to the shaft, the hydraulic circuit providing a hydraulic pressure, and

the method comprising:

detecting a hydraulic pressure of the hydraulic circuit using a pressure sensor; and

using the output signal from the pressure sensor to electronically control a rotational speed of the generator, including

providing a desired hydraulic pressure signal indicative of a desired hydraulic pressure associated with a prescribed generator speed;

receiving the actual hydraulic pressure signal indicative of an actual hydraulic pressure; and

computing a pressure error signal between the desired and actual hydraulic pressure signals.

2. The method of claim 1 , further comprising:

computing, on the basis of the pressure error signal, a first parameter of the desired configuration of the hydraulic unit.

3. The method of claim 2 , further comprising:

receiving an offset signal; and

computing a second parameter of the desired configuration of the hydraulic unit on the basis of the offset signal and the first parameter.

4. The method of claim 3 , wherein the desired configuration of the hydraulic unit is determined on the basis of the first and second parameters.

5. The method of claim 3 , wherein the first and second parameters are responsive to a change in the rotational speed of the generator.

6. The method of claim 3 , wherein the second parameter conforms with a predetermined limitation.

7. The method of claim 6 , wherein the predetermined limitation includes a limitation on a rate of change in the second parameter.