Fuel control method for gas turbine, control device for executing said method, and gas turbine installation provided with said control device

A control device for a gas turbine comprising:

• the control device configured to:
• output a target value that is equivalent to a target rotation speed of the gas turbine;
• obtain a target value deviation, the target value deviation being a deviation of the target value with respect to an actual rotation speed equivalent value that is equivalent to an actual rotation speed of the gas turbine;
• detect a variation of the actual rotation speed of the gas turbine, wherein the variation is between a first actual rotation speed and a second actual rotation speed after a delay of a predetermined period of time, and output an indication of whether the actual rotation speed equivalent value has increased or decreased in accordance with the variation:
• obtain an upper limit deviation, the upper limit deviation being a deviation of a set upper limit output of the gas turbine with respect to an actual output of the gas turbine;
• obtain a lower limit deviation, the lower limit deviation being a deviation of the actual output of the gas turbine with respect to a set lower limit output of the gas turbine;
• and-
• change any one of the target value, the actual rotation speed equivalent value, and the target value deviation such that
• the target value deviation decreases in a case where the actual rotation speed equivalent value has decreased when the upper limit deviation is smaller than a first previously determined value, and
• the target value deviation increases in a case where the actual rotation speed equivalent value has increased when the lower limit deviation is smaller than a second previously determined value;
• and determine a fuel equivalent value that is equivalent to a flow rate of fuel supplied to the gas turbine in accordance with the target value deviation such that
• the fuel equivalent value decreases and the actual output of the gas turbine remains below the set upper limit output in a case where the target value deviation decreases,
• and the fuel equivalent value increases and the actual output of the gas turbine remains above the set lower limit output in a case where the target value deviation increases.