band if the frequency discrepancy lies within the dead band the required pressure value correction is equal to zero in the dynamic block 55 the required pressure value correction receives in impressed form a signal decaying with time if the switch 56 is in the on position the required pressure value correction determined in this way is passed on via the output 38 at which is present the required pressure value correction dynamically evaluated by the signal decaying with time to the pressure control system corresponding to the pressure stage by this the discrepancy can be taken into account in this pressure control system on the basis of the required value correction this results in the pressure control system remaining u201c at rest u201d due to the application of the required value correction and not counteracting the change in the actual value the required pressure value correction with the applied signal decaying with time u2014 evaluated by an evaluation factor 62 which converts the required pressure value correction into the corresponding valve setting u2014 is passed on simultaneously via the output 39 to the pressure control system output of the high pressure part of the steam turbine this effects the corresponding adjustment to the setting value of the control valve the dynamically evaluated required pressure value correction u2014 evaluated by the evaluation factor 61 which converts the required pressure value correction into the corresponding valve setting u2014 is correspondingly present at the medium pressure control output 40 the control discrepancy is also corrected for the medium pressure stage by the dynamically and statically evaluated required pressure value correction 41 being present in the pressure control system and therefore likewise holding the pressure control system.