Method for operating a steam turbine

1. A method for operating a steam turbine, wherein the steam turbine has a rotatably mounted steam turbine rotor and a housing which is arranged around the steam turbine rotor, wherein the rotor is coupled in terms of torque to a generator rotor of an electrical generator, the method comprising:

cooling the generator with a cooling medium, wherein a cooling pressure of the cooling medium in the generator is set,

exerting a torque by the generator rotor on the steam turbine rotor,

changing the torque from the generator rotor to the steam turbine rotor by means of a change in the cooling pressure.

2. The method as claimed in claim 1 ,

wherein an increase in the cooling pressure leads to an increase in the torque from the generator rotor to the steam turbine rotor.

3. The method as claimed in claim 1 ,

wherein a reduction in the cooling pressure leads to a reduction in the torque from the generator rotor to the steam turbine rotor.

4. The method as claimed in claim 1 ,

wherein the cooling pressure is changed during a startup process of the steam turbine.

5. The method as claimed in claim 1 ,

wherein the cooling pressure is changed during the shutdown process of the steam turbine.

6. The method as claimed in claim 1 ,

wherein an automation system for regulating the cooling pressure is designed such that an increase in the pressure and/or in the mass flow of the steam into the steam turbine is realized within specific limits.

7. The method as claimed in claim 6 ,

wherein the automation system is furthermore designed such that a change, or a reduction, in the mass flow of the steam into the steam turbine is realized within specific limits.

8. The method as claimed in claim 7 ,

wherein the change in the mass flow is realized in a manner dependent on the braking load provided by the generator.

9. The method as claimed in claim 1 ,

wherein the cooling medium comprises air.