We claim:
1. A steam turbine system, comprising:
a plurality of blade stages arranged axially along a first shaft;
an impulse stage configured upstream of the plurality of blade stages, the
impulse stage having an impulse wheel and a casing, the casing including a
plurality of inlet sections with each of the plurality of inlet sections having a
corresponding nozzle group and operatively connected to a corresponding control
valve controlling a first steam flow through the corresponding nozzle group;
a first inlet configured to provide the first steam flow through the impulse
stage and the plurality of blade stages; and,
a second inlet configured to provide a second steam flow to the plurality of
blade stages and bypassing the impulse stage.

2. The system as claimed in claim 1, wherein at least one of the plurality of
nozzle groups has a different number of nozzles than the remaining nozzle groups.

3. The system as claimed in claim 1, wherein each of the nozzle groups of
the impulse stage are configured to direct the first steam flow to bypass at least
one of the plurality of blade stages.
4. The system as claimed in claim 1, further comprising a first housing
enclosing the plurality of blade stages and the impulse stage.
5. The system as claimed in claim 1, further comprising a first housing
enclosing the plurality of blade stages, and a second housing enclosing the
impulse stage arranged on the first shaft.
6. The system as claimed in claim 1, further comprising a first housing
enclosing the plurality of blade stages, and a second housing enclosing the
impulse stage arranged on a second shaft.
7. A power plant, comprising:
a steam source for generating a steam flow;
a high pressure turbine system having:
a plurality of blade stages arranged axially along a first shaft;
an impulse stage configured upstream of the plurality of blade
stages, the impulse stage having an impulse wheel and a casing, the casing
including a plurality of inlet sections with each of the plurality of inlet sections
having a corresponding nozzle group and operatively connected to a
corresponding control valve controlling a first steam flow through the
corresponding nozzle group;
a first inlet configured to provide the first steam flow through the
impulse stage and the plurality of blade stages; and,
a second inlet configured to provide a second steam flow to the
plurality of blade stages and bypassing the impulse stage;
an intermediate pressure turbine system and a low pressure turbine system
fluidly coupled to the high pressure turbine system; and,
a first generator driven by the first shaft.

8. The power plant as claimed in claim 7, wherein at least one of the plurality
of nozzle groups of the casing has a different number of nozzles than the
remaining nozzle groups.

9. The power plant as claimed in claim 7, wherein each of the corresponding
nozzle groups of the impulse stage are configured to direct the first steam flow to
bypass at least one of the plurality of blade stages.
10. The power plant as claimed in claim 7, further comprising a first housing
enclosing the plurality of blade stages and the impulse stage of the high pressure
steam turbine system.
11. The power plant as claimed in claim 7, further comprising a first housing
enclosing the plurality of blade stages, and a second housing enclosing the
impulse stage arranged along the first shaft.
12. The power plant as claimed in claim 7, further comprising a first housing
enclosing the plurality of blade stages, and a second housing enclosing the
impulse stage arranged along a second shaft driving a second generator.
13. An impulse stage system for a steam turbine system, the impulse stage
system comprising:
an impulse wheel arranged on a first shaft; and,
a casing including a plurality of inlet sections, wherein each of the
plurality of inlet sections have a corresponding nozzle group and operatively
connected to a corresponding control valve controlling a first steam flow through
the corresponding nozzle group
a first inlet configured to feed the first steam flow through the impulse
stage.
14. The system as claimed in claim 13, wherein at least one of the
corresponding nozzle groups has a different number of nozzles than the remaining
nozzle groups.