Method of estimating the maximum power generation capacity and for controlling a specified power reserve of a single cycle or combined cycle gas turbine power plant, and a power generating system for use with said method

1. A method of estimating the maximum power generation capacity of a gas turbine power plant having a microprocessor coupled to a memory arranged as a controller which regulates an operation of the power plant, the method comprising the controller:

calculating an actual power output and a maximum power generation capacity of the gas turbine power plant based on a mathematical model of the gas turbine power plant;

measuring the actual power output of the gas turbine power plant;

comparing the calculated actual power output and the measured power output to derive a model-estimation error;

processing the model-estimation error to generate a correction signal; and

applying the correction signal to the calculated maximum power generation capacity to obtain a corrected estimate of the maximum power generation capacity of the gas turbine power plant.

2. A method according to claim 1 , wherein the mathematical model of the gas turbine power plant is a control-oriented and dynamic model.

3. A method according to claim 1 , wherein the mathematical model relies on an input vector that comprises one or more of manipulated variables of the controller, which regulates the operation of the power plant.

4. A method according to claim 1 , comprising the controller:

determining base load values of the manipulated variables; and

calculating the maximum power generation capacity of the gas turbine power plant with the base load values.

5. A method according to claim 1 , wherein the mathematical model relies on an input vector that comprises signals indicative of disturbances.

6. A method according to claim 1 , wherein the mathematical model relies on an input vector that comprises power plant process measurements.

7. A method according to claim 1 , wherein limiting values of the power plant process measurements are used to calculate the maximum power generation capacity of the gas turbine power plant.

8. A method according to claim 1 , wherein the mathematical model relies on at least one of the following signals: a signal indicative of a position of variable inlet guide vanes, a signal indicative of a base load position of the variable inlet guide vanes, signal(s) indicative of turbine inlet temperature(s), signal(s) indicative of base load value(s) of the turbine inlet temperature(s), signal(s) indicative of mixed turbine inlet temperature(s), signal(s) indicative of base load value(s) of the mixed turbine inlet temperature(s), signal(s) indicative of the turbine outlet temperature(s), signal(s) indicative of base load value(s) of the turbine outlet temperature(s), a signal indicative of a gas turbine compressor inlet temperature, a signal indicative of a coolant temperature of a steam turbine condenser, a signal indicative of fuel type used, a signal indicative of quality of fuel used, signals indicating a state of power augmentation measures, a signal indicative of gas turbine compressor outlet temperature, and a signal indicative of gas turbine compressor outlet pressure.

9. A method according to claim 1 , comprising the controller:

evaluating a quotient of the measured power output and the calculated actual power output yielding a multiplicative model-estimation error; and

multiplying the calculated maximum power generation capacity by the correction signal to obtain a corrected estimate of the maximum power generation capacity of the gas turbine power plant.

10. A method according to claim 1 , comprising the controller:

evaluating a difference of the measured power output and the calculated actual power output, yielding an additive model-estimation error; and

adding the correction signal to the calculated maximum power generation capacity to obtain a corrected estimate of the maximum power generation capacity of the gas turbine power plant.

11. A method according to claim 1 , comprising the controller:

separating the model-estimation error by dynamic filtering into a low-frequency part and a high-frequency part, and the low-frequency part is subsequently used as correction signal.

12. A method according to claim 1 , wherein the gas turbine power plant is of single cycle type.

13. A method according to claim 1 , wherein the gas turbine power plant is of combined cycle type.

14. A power generating system, comprising:

a gas turbine power plant;

a controller for regulating operation of the gas turbine power plant; and

an estimation unit for:

calculating an actual power output and a maximum power generation capacity of the gas turbine power plant based on a mathematical model of the gas turbine power plant;

measuring the actual power output of the gas turbine power plant;

comparing the calculated actual power output and the measured power output to derive a model-estimation error;

processing the model-estimation error to generate a correction signal;

applying the correction signal to the calculated maximum power generation capacity to obtain a corrected estimate of the maximum power generation capacity of the gas turbine power plant; and

continuously providing an estimate of the maximum power generation capacity of the gas turbine power plant.

15. A power generating system according to claim 14 , comprising:

a display for displaying the estimate of the maximum power generation capacity of the gas turbine power plant to the operator of the power plant.

16. A power generating system according to claim 14 , wherein the gas turbine power plant is of single cycle type.

17. A power generating system according to claim 14 , wherein the gas turbine power plant is of combined cycle type.