Patent ID: 8175786

Claim:
A method for operating a gas turbine ( 10 ), which feeds power to a local isolated power supply network, and which comprises a compressor ( 11 ) for compressing combustion air which is drawn in from the environment, a combustion chamber ( 15 ) for combusting supplied fuel using the compressed combustion air, a turbine ( 12 ) which is driven by hot gas from the combustion chamber ( 15 ), and a generator ( 13 ), which is driven by the turbine ( 12 ), for generating electric power, the method comprising: providing at least one transducer ( 23 , . . , 33 ) for measuring or determining at least one of the following parameters of the gas turbine: an ambient temperature (T 1 ), a compressor inlet temperature (T 2 ), a compressor outlet temperature a turbine exhaust temperature an ambient air pressure a total or static absolute or gauge pressure (p 3 ) at a compressor outlet ( 19 ), a total or static absolute or gauge pressure at a turbine inlet ( 21 ), a pressure loss between compressor outlet ( 19 ) and turbine inlet ( 21 ), a speed (n GT ) of the gas turbine ( 10 ) or a frequency of a power supply network, a measured or predetermined mass flow (m fuel ) of the fuel which is fed to the combustion chamber ( 15 ), and a lower heating value (LHV) of the fuel; calculating an effective thermal output power (P GT ) of the gas turbine ( 10 ) from the measured or determined parameters; and controlling the gas turbine ( 10 ) based on the calculated effective thermal output power (P GT ), wherein the effective thermal output power (P GT ) of the gas turbine ( 10 ) is calculated in accordance with the equation P GT αƒ1(p 3 )·ƒ2(m fuel )·ƒ3(LHV)·ƒ4(n GT )·ƒ5(T 2 ) where f 1 , . . ,f 5 are functions which are to be determined for a respective case, p 3 is the compressor outlet pressure, m fuel is the fuel mass flow, LHV is the lower heating value of the fuel, n GT is the speed of the gas turbine ( 10 ), and T 2 is the compressor inlet temperature.