Method for controlling a combustion apparatus and control device

A control device, comprising:

• a sensor for measuring a parameter (p) related to a combustion state of a combustion apparatus;
• a controller connected with the sensor and configured to:
• receive measured values (p1) of the parameter (p) from the sensor and to determine a time series (S0) of the measured values of the parameter (p);
• shift the time series (S0) by a variable time delay (96var) for determining a time-shifted signal (Sτ), and form a difference (Sτ- S0) between the time-shifted signal (Sτ) and the time series (S0) for determining a time dependent first signal (S1), so that a norm of the difference (Sτ- S0) between the time-shifted signal (Sτ) and the time series (S0) is lowest;
• determine a time dependent second signal (S2) different to the first signal (S1), wherein the second signal (S2) is determined based on a frequency (fOL) of a desired periodic state of the combustion apparatus and/or wherein determining the second signal (S2) comprises shifting the time series (S0) by a set time delay (τset);
• and
• output a function (F) of the first signal (S1) and the second signal (S2) as a primary control signal (S);
• and
• an actuator connected with the controller and configured to convert the primary control signal (S) into a secondary control signal (p2) suitable to influence the combustion apparatus.