Burner for a gas turbine and method for operating the burner

A method for operating a burner which comprises a control unit, a combustion chamber, a pressure sensor and fuel stages, each fuel stage being arranged to supply fuel with a respective mass flow to the combustion chamber, wherein the mass flows are controlled by the control unit, the method comprising:

• a) supplying the fuel to the combustion chamber and combusting the fuel in the combustion chamber;
• b) measuring a pressure sequence in the combustion chamber or in the burner using the pressure sensor and transferring the pressure sequence to the control unit;
• c) performing a Fourier transformation on a multitude one of determined timespans of the pressure sequence to provide, for each determined timespan, a respective pressure spectrum having a respective maximum within a frequency band;
• d) comparing each of the maxima with a predefined threshold;
• e) counting the number of maxima exceeding the predefined threshold within a predetermined number of the timespans;
• f) controlling the mass flows based on the comparison of each maximum with the predefined threshold and based on the number of maxima exceeding the predefined threshold to reduce and/or to control pressure fluctuations in the combustion chamber.