Protection process and control system for a gas turbine

1. A process for protection of a gas turbine from damage caused by pressure pulsations, the process comprising:

measuring pressure pulsations occurring during the operation of the gas turbine;

generating a pulsation-time signal from the measured pressure pulsations;

transforming the pulsation-time signal into a pulsation-frequency signal;

determining from the pulsation-frequency signal a pulsation level for at least one specified monitoring frequency band, wherein determining the pulsation level comprises determining from the maximum pulsation value in the monitoring frequency band;

monitoring the pulsation level for the occurrence of at least one trigger condition;

carrying out, when the at least one trigger condition occurs, a protective action; and

shifting the monitoring frequency band upon a frequency shift of the maximum pulsation value, to follow the maximum pulsation value, so that the maximum pulsation value remains within the monitoring frequency band.

2. A process according to claim 1 , wherein determining the pulsation level comprises summation, integration, averaging, or combinations thereof, of the pulsation values in the monitoring frequency band.

3. A process according to claim 1 , wherein the monitoring frequency band is defined such that when precisely one previously known critical pulsation again occurs, the monitoring frequency band lies with its pulsation frequency in said monitoring frequency band.

4. A process according to claim 1 , further comprising:

generating, from the pulsation level, a pulsation-level time signal; and

monitoring the pulsation-level time signal for the at least one trigger condition.

5. A process according to claim 4 , further comprising:

averaging the pulsation-level time signal.

6. A process according to claim 1 , wherein generating the pulsation-frequency signal from the pulsation-time signal comprises generating with a numerical-mathematical transformation.

7. A process according to claim 6 , wherein the numerical-mathematical transformation comprises a fast Fourier transform or a discrete Fourier transform.

8. A process according to claim 1 , wherein said monitoring the pulsation level for the occurrence of at least one specified trigger condition comprises monitoring separately for each monitoring frequency band.

9. A process for protection of a gas turbine from damage caused by pressure pulsations, the process comprising:

measuring pressure pulsations occurring during the operation of the gas turbine;

generating a pulsation-time signal from the measured pressure pulsations;

transforming the pulsation-time signal into a pulsation-frequency signal;

determining from the pulsation-frequency signal a pulsation level for at least one specified monitoring frequency band;

monitoring the pulsation level for the occurrence of at least one trigger condition; and,

carrying out, when the at least one trigger condition occurs, a protective action

examining, when a pulsation occurs, whether said pulsation is a harmonic of a pulsation from a lower frequency range; and

monitoring an associated pulsation level only if the associated pulsation is not a harmonic.

10. A process for protection of a gas turbine from damage caused by pressure pulsations, the process comprising:

measuring pressure pulsations occurring during the operation of the gas turbine;

generating a pulsation-time signal from the measured pressure pulsations;

transforming the pulsation-time signal into a pulsation-frequency signal;

determining from the pulsation-frequency signal a pulsation level for at least one specified monitoring frequency band;

monitoring the pulsation level for the occurrence of at least one trigger condition;

carrying out, when the at least one trigger condition occurs, a protective action;

wherein the at least one trigger condition comprises a trigger strategy including a trigger counter (AZ) and a reset counter (RZ);

wherein the trigger counter (AZ) comprises adding the time (t) during which the pulsation level lies above a specified level limit value (PL limit ) to the preceding counter reading;

wherein the at least one trigger condition occurs and the specified protective action is started as soon as the trigger counter (AZ) reaches a specified trigger counter reading (AZ limit );

wherein the reset counter (RZ) comprises adding the time (t) during which the pulsation level (PL) does not lie above the level limit value (PL limit ) to a counter reading that has been reset to zero; and

further comprising setting to zero the counter reading of the trigger counter (AZ) as soon as the reset counter (RZ) reaches a specified reset counter reading (RZ limit ).

11. A process according to claim 10 , further comprising:

terminating the protective action and setting to zero the counter reading of the trigger counter (AZ) if the reset counter (RZ) reaches a specified counter reading (RZ SAZ ) during the protective action.

12. A process according to claim 11 , wherein said specified counter reading (RZ SAZ ) is smaller than the reset counter reading (RZ limit ).

13. A control system for a gas turbine comprising:

a pulsation measuring device which includes and is configured and arranged to measure with a sensor the pressure pulsations occurring during the operation of the gas turbine and generates a pulsation-time signal (PZS) correlated with said pressure pulsations;

a pulsation evaluation device configured and arranged to transform the pulsation-time signal (PZS) into a pulsation-frequency signal (PFS), determine from the pulsation-frequency signal (PFS) for at least one specified monitoring frequency band a pulsation level (PL), monitor the pulsation-frequency signal for the occurrence of at least one specified trigger condition, and when the at least one trigger condition occurs, generate a trigger signal;

a control device configured and arranged to perform a specified protective action when the trigger signal is present; and

a galvanically decoupled connection configured and arranged to transmit the pulsation-time signal (PZS) between the pulsation measuring device and pulsation evaluation device.

14. A control system according to claim 13 , further comprising:

a monitoring device in communication with the pulsation evaluation device and configured and arranged to permit configuring of the pulsation evaluation device, visualization of said pulsation monitoring, storing the pulsation monitoring process, or combinations thereof.

15. A control system according to claim 14 , further comprising:

a display system, a diagnosis system or both;

wherein the monitoring device is connected to the display system, to the diagnosis system, or to both.