Gas turbine controller of single-shaft combined cycle power generating plant and gas turbine output calculating method

Abstract

A gas turbine control apparatus for a single-shaft type combined cycle power plant is provided by which gas turbine output is accurately computed during a circulating water reversing wash operation. Vacuum down amount is computed from a generator output signal ( ) immediately before the mentioned reversing wash operation and is corrected by being multiplied by a valve opening correction factor computed from a condenser reversing valve opening signal ( ) and a sea water temperature correction factor computed from a condenser reversing valve inlet sea water temperature signal ( ). A condenser vacuum at the time of the reversing wash operation is computed by the corrected vacuum down amount being subtracted therefrom. A vacuum correction factor is computed based on the computed condenser vacuum. A reference steam turbine output is computed based on a post-intercept valve steam pressure signal ( ) and a steam turbine output signal ( ) is computed by multiplying the reference steam turbine output by the vacuum correction factor. A gas turbine output signal ( ) is computed by subtracting the steam turbine output signal ( ) from the generator output signal ( ).