DE102006004163A1 - Protecting gas turbine against pressure pulsation damage involves monitoring pulsation level in pulsation frequency band for at least one triggering condition, carrying out predefined protective action if triggering condition(s) occurs - Google Patents

Abstract

The invention relates to a method for protecting a gas turbine (1) against damage by pressure pulsations (P),
in which a pulsation level (PL) is monitored with regard to the occurrence of at least one predetermined triggering condition, at least in a monitoring frequency band (12) of the pulsations (P),
in which a predetermined protection action (16) is carried out when the triggering condition occurs,
in which the at least one triggering condition has a tripping strategy which works with a tripping counter (AZ) and with a reset counter (RZ),
in which the trigger counter (AZ) sums the time (t) during which the respective pulsation level (PL) is above a predetermined level _limit value (PL _limit ) to the respectively preceding counter reading,
in which the trigger condition occurs and the predetermined protection action (16) is started as soon as the trigger counter (AZ) reaches a predetermined trigger count (AZ _limit ),
- in which the reset counter (RZ) the time (t) during which the respective pulsation level (PL) is not above the level _limit (PL _limit ), each summed to a zero count,
- In which the count of the trigger counter (AZ) is set to zero as soon as the reset counter (RZ) reaches a predetermined reset count (RZ _limit ).

Description

technical area

The The present invention relates to a method of protecting a gas turbine from damage by pressure pulsations. The invention also relates to a Control system for carrying out a such protection.

in the Operation of a gas turbine can, especially in a combustion chamber the gas turbine, due to the combustion process to pressure pulsations come. Such pulsations can, if they have high amplitudes or last too long, serious damage on the structure or on individual components of the gas turbine, in particular on whose combustion chamber, cause what the lifetime of the gas turbine shortened. Furthermore, you can Pulsations malfunctions signal the combustion reaction, for example, by fluctuations in the fuel and / or fresh air supply or by abrupt Load changes can be caused. In individual cases can the pulsations also the combustion reaction or its flame Clear, which leads to the formation of an explosive gas mixture.

modern Gas turbines are therefore equipped with a pulsation protection system, on the one hand occurring during operation of the gas turbine pressure pulsations and, on the other hand, when defined triggering conditions occur, like the sudden one Occurrence of pulsations with very high amplitudes or the occurrence pulsations of medium amplitude during a longer period, appropriate protection actions causes, such as the Switch off the gas turbine. The measurement of pressure pulsations can for example, with the help of a corresponding pressure sensor, by means of which a pulsation time signal can be generated, which with correlated to the occurring pulsations. Under a "pulsation time signal" is present in the Connected a signal understood that the amplitudes of the pulsations (Ordinate values) depending on represents the time (abscissa values). The thus determined pulsation time signal can now be divided into certain monitoring frequency bands which can be individually analyzed and evaluated. there it may be appropriate within the respective monitoring frequency band to perform an averaging.

A such approach to protect the gas turbine from damage however, by pressure pulsations works comparatively inaccurate. Out security It may therefore become protective actions, for example, an emergency shutdown the gas turbine, even if this is not necessary in itself would. A unnecessary However, shutdown of the gas turbine is expensive and expensive loss of revenue connected.

Presentation of the invention

Here The invention aims to remedy this. The invention, as in the claims is employed dealing with the problem, for the protection of a gas turbine from damage by pressure pulsations to show an improved way, in particular a comparatively high reliability has and unnecessary Protective actions if possible avoids.

According to the invention this Problem with the objects the independent one claims solved. Advantageous embodiments are the subject of the dependent Claims.

The The invention is based on the general idea for at least one triggering condition triggering strategy provided. This triggering strategy according to the invention Characterized by the fact that they are equipped with a trip counter and works with a reset counter, wherein the trip counter the Time, while the respective pulsation level is above a predetermined level limit, summed up to the previous counter reading. The trigger condition then occurs and the predetermined protection action is then started, if the trip counter one predetermined trigger count reached. In contrast, the reset counter sums the time during which the respective pulsation levels not above the aforementioned level limit is in each case set to a zero counter reading. Furthermore, will always then the meter reading of the trigger counter Zeroed as soon as the reset counter reaches a predetermined value Reset count reached. Lead by the triggering strategy according to the invention on the one hand critical pulsation frequencies, their amplitudes for a long time is above the predetermined level limit, to trigger the respective protection action. On the other hand also solves a sequence of critical Pulsation amplitudes, which occur only for a relatively short time, however, follow each other with comparatively small distances, as well the respective protection action.

On the other hand, the trip counter is reset to zero if no critical pulsation amplitudes occur during a period of time defined by the predetermined reset count. In this way, short-term, temporary and harmless disturbances of serious Disturbing the pulsation behavior can be distinguished. Accordingly, an unnecessary shutdown of the gas turbine can be avoided by this protection method. Furthermore, this protection method can cover various triggering conditions. For example, the time setting and / or the trigger level for different operating conditions of the gas turbine, such as normal operation, startup or shutdown, be chosen differently.

at In a particularly advantageous embodiment, the pressure pulsations with Help a pulsation frequency signal are monitored. Under a "pulsation frequency signal" is present in the Connected a signal understood that the amplitudes of the pulsations (Ordinate values) depending on represents the frequency (abscissa values). Let such a pulsation frequency signal especially predetermined monitoring frequency bands just cut it out. Furthermore, the frequency bands can be comparatively narrowly selected become what it enables certain Targeted and separate monitoring of pulsation frequencies. The invention is based doing so also on the realization that disturbing or critical, so dangerous Pulsation frequencies relatively close to harmless pulsation frequencies can lie so that a comparatively broad monitoring frequency band is systemic also detects harmless pulsation frequencies and accordingly not from can distinguish the critical pulsation frequencies. The width the monitoring frequency bands can with a pulsation-time signal by means of conventional band filter not arbitrary be chosen small. This affects the more pronounced the larger the frequencies to be filtered out are. Since the critical pulsation frequencies depend on the type of gas turbine, especially at more than 1 kHz, which are at a pulsation time signal selectable monitoring frequency bands regularly relatively wide. In contrast to this, the monitoring frequency bands can be used for Pulsation frequency signal very tight, so it in particular possible is to exclude closely adjacent harmless pulsation frequencies from pulsation monitoring. this leads to to the fact that with the help of the invention falsely triggered protection actions not or only diminished. In particular, it can unnecessary Standstill pages for the Gas turbine can be avoided. This combination can be a special effective protection of the gas turbine against damage by pressure pulsations be achieved.

at a preferred embodiment a pulsation level that monitors within the respective monitoring frequency band is determined by the maximum pulsation value in the respective monitoring frequency band be formed. This means, within the respective monitoring frequency band in each case the pulsation maximum (peak) is monitored. In contrast to an alternative possible Summation or integration or general averaging guaranteed The supervision the Pulsationsmaximums that with high probability excluding the Level of actually dangerous or critical pulsation frequency is observed, indicating the reliability the surveillance improved.

According to one Another advantageous development, the monitoring frequency band at a Frequency shift of the maximum pulsation value to the maximum Tracked Pulsationswert be such that the maximum pulsation level is always within the monitoring frequency band remains. In this embodiment considered, that is the respective monitoring frequency band can change assigned critical pulsation frequency. For example, the measured pulsation frequency of the speed of sound at the point of origin the pulsations, which in turn is temperature-dependent. In operation of the gas turbine can change in particular in the combustion chamber, the temperature, which is a corresponding change the speed of sound results and thus to a shift in the critical pulsation frequencies leads. Other parameters, which affect the Pulsationsfrequenz are, for example, the gas composition. These can change that that, for example, another fuel is used, and / or another fuel-air mixture (λ value) and / or another Fuel-water mixture (Ω value) set becomes. The automatic tracking of the monitoring frequency band can the ones to be monitored critical pulsation frequency does not move out of the monitoring frequency band. Accordingly increased reliability the Pulsationsschutzes even at relatively narrow monitoring frequency bands.

Further provide important features and advantages of the present invention from the subclaims, from the drawings and from the associated description of the figures the drawings.

Short description the drawings

preferred embodiments The invention are illustrated in the drawings and in the following description explains where like reference numerals refer to the same or similar or functionally identical components. Show, respectively schematically

1 a diagram in the manner of a flow chart of the protection method according to the invention in a specific embodiment,

2 a view like in 1 but for another part of the process,

3 a circuit diagram-like schematic diagram of a control system according to the invention.

Ways to execute the invention

Corresponding 1 includes a gas turbine 1 usually a compressor 2 , a combustion chamber 3 as well as a turbine 4 , In the gas turbine 1 , in particular in the combustion chamber 3 , can during operation of the gas turbine 1 Pressure pulsations P occur. These pressure pulsations or pulsations P are for example in the region of the combustion chamber 3 with the help of a suitable sensor 5 measured. The sensors 5 may, for example, a microphone, a dynamic pressure booster, a piezoelectric pressure transducer, a piezoresistive pressure transducer or other suitable for detecting the pressure pulsations device. Likewise, the pressure pulsations P can be determined, for example, indirectly via the acceleration of combustion chamber components. The measured pressure pulsations P can, for example, by means of a suitable amplifier 6 be processed to generate a pulsation time signal PZS. The pulsation time signal PZS represents the dependence of the pulsation P on the time t. In 1 is this connection through a diagram 7 visualized, in which the pulsation P forms the ordinate, while the time t forms the abscissa.

In the present invention, the pulsation time signal PZS is now preferably transformed into a pulsation frequency signal PFS, which includes the dependence of the pulsation P on the frequency f (frequency spectrum). The thus determined pulsation frequency signal PFS is in 1 through a diagram 8th visualized whose abscissa is formed by the frequency f and its ordinate by the pulsation P. The pulsation frequency signal PFS can be determined from the pulsation time signal PZS by means of a suitable mathematical, in particular numerical, method, for example with the aid of a Fourier transformer 9 be derived, which performs a corresponding Fourier analysis for this purpose. The Fourier transform is in 1 through a diagram 10 symbolically represented. The Fourier transformer 9 can work, for example, by means of FFT (Fast Fourier Transformation) or by means of DFT (Discrete Fourier Transformation). The Fourier transformer 9 can be a rectifier 11 , In particular, an RMS rectifier downstream, where RMS stands for Root Mean Square (root mean square), here RMS signal level.

Of Furthermore, the pulsation frequency signal PFS can additionally be processed become. For example, you can disorders repressed become.

Within the pulsation frequency signal PFS at least a predetermined monitoring frequency band 12 supervised. Preferably, however, a plurality of predetermined monitoring frequency bands 12 supervised. The monitoring frequency bands 12 are in another diagram 13 marked with braces.

In principle it is possible to use the monitoring frequency bands 12 to choose so that several disturbing or critical or dangerous pulsation frequencies to be monitored in the respective monitoring frequency band 12 lie. However, preferred here is an embodiment in which in each monitoring frequency band 12 exactly one to be monitored, critical pulsation frequency is.

A significant advantage of the present invention is seen in that within the pulsation frequency signal PFS the monitoring frequency bands 12 can be selected with comparatively small frequency bandwidths. This makes it possible to clearly distinguish critical, dangerous pulsation frequencies from uncritical, harmless pulsation frequencies and thus distinguish them, even if the harmless pulsation frequencies are relatively close to critical, dangerous pulsation frequencies.

For each predetermined monitoring frequency band 12 a pulsation level PL is determined. This pulsation level PL correlates with a pulsation amplitude of the monitored pulsation frequency within the respective monitoring frequency band 12 ,

The determination of the pulsation level PL can be carried out in different ways. For example, within the respective monitoring frequency band 12 an average of the in the monitoring frequency band 12 occurring pulsation amplitudes are formed. In particular, rms values or quadratic averages can also be formed here. The averaging is particularly suitable for the determination of the pulsation level PL, if the respective monitoring frequency band 12 is assigned more than a predetermined critical pulsation frequency.

Alternatively, in a preferred embodiment within the respective monitoring frequency band 12 the pulsation level PL da be determined by that for the pulsation level PL respectively the maximum pulsation value (peak value), in the respective monitoring frequency band 12 occurs, is used. This relationship is in the diagram 13 shown. The pulsation maxima are each formed by peaks of the pulsation frequency signal PFS and thereby define the respective pulsation level PL.

According to the invention, the pulsation levels PL are now monitored with regard to the occurrence of at least one predetermined triggering condition. This monitoring is in 1 by way of example in another diagram 14 reproduced, which represents the time course of the pulsation level PL. It forms in the diagram 14 the pulsation level PL is the ordinate, while the abscissa is formed by the time t. The diagram 14 shows here the time course of the pulsation level PL, so a pulsation level-time signal PLZS for a single monitoring frequency band 12 and thus in particular for only one critical pulsation frequency to be monitored.

Accordingly Here, a pulsation level-time signal PLZS is generated, which then monitored with regard to the at least one triggering condition becomes. It is basically possible, this Pulsation level-time signal PLZS prepare appropriately. In particular, here too an averaging can take place, in particular by Determination of the RMS value.

The pulsation levels PL become for the different monitoring frequency bands 12 appropriately independently monitored.

As a triggering condition, for example, a maximum pulsation level PL _{max can be} used. As soon as the pulsation level PL reaches the maximum pulsation level PL _max , this triggering condition is present. This is in the diagram 14 given by the intersection of the pulsation level-time signal PLZS with the maximum value of the pulsation level PL _{max shown} in the diagrams 13 and 14 With 15 is designated. The point of intersection 15 thus represents the occurrence of said trigger condition, which triggers a predetermined protection action according to the invention, which is shown here in the diagrams 13 and 14 through an arrow 16 is symbolized. This protection action 16 For example, a withdrawal of the fuel supply and / or enrichment of the fuel / air mixture or switching off the combustion chamber 3 or just an alerting the operator. Likewise, other protective reactions 16 or combinations of such measures possible.

If - as here - the pulsation level PL within the individual monitoring frequency bands 12 is formed by the peak value (peak) occurring therein, according to an advantageous embodiment, it is possible to use the monitoring frequency band 12 not statically set, but this dynamic to shifts of the maximum pulsation value, so here to adjust the pulsation level PL. This is done by a corresponding shift of the respective monitoring frequency band 12 such that the peak of the pulsation frequency signal PFS within the monitoring frequency band 12 remains. A shift of the critical pulsation frequency to be monitored along the abscissa, ie a frequency shift, occurs, for example, when inside the combustion chamber 3 For example, by changing the temperature changes the speed of sound. In this way it can be avoided that the pulsation frequency to be monitored from the monitoring frequency band 12 migrates, even if for the monitoring frequency band 12 only a very small frequency bandwidth is selected.

For processing the pulsation frequency signal PFS, it is also possible to hide harmonics. For example, this is first checked when a pulsation occurs in a corresponding test band, if this could be a harmonic of a pulsation (fundamental frequency, base) from a low frequency range. If this is the case, all harmonics are deleted from the considered part of the pulsation frequency signal PFS, that is, the signal amplitudes over the respective frequencies are set to zero. Pulsation levels are thus taken into account in the monitoring only if the associated pulsation is not a harmonic. Because the harmonics underlying base pulsation anyway in its own monitoring frequency band 12 supervised.

Corresponding 2 In the case of the invention monitoring of the pulsation level PL or of the pulsation level time signal PLZS takes place in that at least one triggering condition has a special triggering strategy. This tripping strategy works with a tripping counter AZ and with a reset counter RZ. In 2 three diagrams are summarized, of which the upper represents the time course of the pulsation level PL, while the middle shows the time course of the trigger counter AZ and the lower reflects the time course of the reset counter RZ. Accordingly, the upper diagram shows the pulsation level timing signal PLZS, while the lower diagrams represent a trip counter signal AZS and a reset counter signal RZS, respectively.

The upper diagram also contains a level _limit PL _limit . This level limit value PL _limit can be smaller than the pulsation level _maximum PL _max from the diagram 14 according to 1 , While exceeding or reaching the Pulsationspegelmaximums PL _max immediately the protection action 16 triggers, reaching or exceeding the level _limit PL _limit according to the triggering strategy described below does not immediately trigger the protection action 16 , It is basically possible that both trigger conditions can exist side by side.

The trip counter AZ counts the time during which the pulsation level PL is above the level _limit PL _limit . The trip counter AZ always adds this time to a previous counter reading. As soon as the trigger counter AZ reaches a predetermined trigger count AZ _limit , the trigger condition occurs. As a rule, a trigger signal (flag) is set for this, and the respective protection action 16 is started.

In contrast, the reset counter RZ counts the time during which the pulsation level PL is below or not above the level _limit value PL _limit . In contrast to the trip counter AZ, the reset counter RZ adds up to a count set to zero. However, as soon as the reset counter RZ reaches a predetermined reset count RZ _limit , the count of the trigger counter AZ is set to zero.

This triggering strategy will be described again below with reference to the in 2 illustrated example explained in more detail:
At time t ₀ , the monitoring begins. The pulsation level PL is below the level _limit PL _limit . As a result, the reset counter RZ counts from the value zero and sums up the time. At time t ₁ , the pulsation level PL exceeds the level _limit PL _limit . As a result, the trip counter AZ starts counting the time. Since at the beginning the trip counter reading in the example has the value zero, the trip counter starts to accumulate at zero at time t ₁ . At time t ₂ , the pulsation level PL falls below the level _limit PL _{limit again} . As a result, the trip counter AZ stops counting, while the reset counter RZ starts again from zero with its time counting. At time t ₃ , the pulsation level PL again exceeds the level _limit value PL _limit ; the trip counter AZ continues to count, adding up to the previous counter reading. At time t ₄ , the pulsation level PL decreases again below the level _limit PL _limit , so that the trip counter AZ does not continue counting and the reset counter RZ starts again at zero with its time count.

At time t ₅ , the pulsation level PL again exceeds the level _limit value PL _limit , so that the trigger counter AZ adds up again to the previous counter reading. At time t ₆ , the counter reading of the trigger counter AZ reaches the trigger counter reading AZ _limit . Consequently, the triggering condition is present and the protection action 16 is started. For example, an alarm is issued or for the duration of the protection action 16 the fuel supply to the combustion chamber 3 changed. The middle chart also shows the status of the protection action 16 registered, whereby here only a distinction is made between an off state and an on state. The history of the protection action status is in 2 denoted by SAZ. At time t ₆ is thus switched from the off state to the on state.

Through the protection action 16 the pulsation level PL decreases again and falls below the level _limit PL _limit at time t ₇ . As a result, the reset counter RZ starts adding up again from zero to the time. At time t ₈ , the reset counter RZ reaches a counter reading designated RZ _SAZ . With this counter reading RZ _SAZ , on the one hand, the protection action status is changed, that is to say switched over from the on state to the off state. On the other hand, the trip counter AZ is reset to zero at the same time.

Although the reset counter RZ reaches the reset counter RZ _limit at time t ₉ , which in itself resets the counter reading of the trigger counter AZ to zero, this has already been done in the present case since a protective action was previously performed 16 was triggered and ended. Accordingly, the associated counter reading RZ _{SAZ is selected to be} smaller than the reset counter reading RZ _limit .

At time t ₁₀ , the pulsation level PL again exceeds the level _limit PL _limit , so that the trip counter AZ starts counting the time again. In this case, the trip counter AZ starts this time because of the previous reset of the value zero.

At time t ₁₁ , the pulsation level PL drops below the level _limit value PL _{limit again} . Thus, the trip counter AZ stops counting while the reset counter RZ starts counting again from zero. At time t ₁₂ , the reset counter RZ reaches its reset counter RZ _limit , which triggers a reset of the count of the trigger counter AZ to the value zero. Thus, at time t ₁₃ , the trip counter AZ starts again at zero when the pulsation level PL exceeds the level _limit value PL _limit . At time t ₁₄ , the pulsation level PL drops below the level _limit value PL _{limit again} . While the count of the trigger counter AZ is held, the reset counter RZ starts to count from zero again. At time t ₁₅ , the reset counter RZ reaches its reset counter RZ _limit , which is a reset of the trigger counter AZ be acts. At the same time, the pulsation level PL reaches its _limit value PL _limit again at this time t ₁₅ , which immediately triggers counting of the trigger counter AZ. At time t ₁₆ , the pulsation level PL drops below the level _limit value PL _{limit again} . The accumulated count of the trigger counter AZ is held, while the reset counter RZ starts again from zero to count the time.

Corresponding 3 can be a control system 17 the gas turbine 1 a pulsation measuring device 18 , a Pulsationsauswerteeinrichtung 19 and a control device 20 exhibit. Furthermore, also a control device 21 and optionally a display and / or a diagnostic system 22 be provided.

The pulsation measuring device 18 includes the sensors 5 and the signal amplifier 6 and can also have a galvanic separator 23 feature. The pulsation measuring device 18 thus serves to measure the pressure pulsations P at the gas turbine 1 , in particular in the combustion chamber 3 , Furthermore, the pulsation measuring device generates 18 the pulsation time signal PZS.

The pulsation evaluation device 19 includes, for example, a low-pass filter 24 , an analog input 25 , an analog output 26 , as well as a digital input 27 and a digital output 28 , The inputs and outputs 25 to 28 are in a computer 29 integrated, which allows real-time processing of the pulsation time signal PZS. Thus, the Pulsationsauswerteeinrichtung 19 transform the pulsation time signal PZS into the pulsation frequency signal PFS, from the pulsation frequency signal PFS for at least one predetermined monitoring frequency band 12 determine the pulsation level PL, monitor this pulsation level PL with respect to the occurrence of at least one predetermined triggering condition and generate a triggering signal when this at least one triggering condition occurs. The transmission of the pulsation time signal PZS between the pulsation measuring device 18 and the Pulsationsauswerteeinrichtung 19 can be done by a galvanically decoupled connection 30, that is, without direct electrical contact. For example, the signal transmission takes place optically or via a transformer. The galvanic decoupling is here by the galvanic separator 23 reached.

The control device 20 on the one hand controls the normal operation of the gas turbine 1 and made possible by their integration into the control system 17 the execution of predetermined protective actions, if the respective trigger signal is present. This trigger signal receives the control device 20 from the Pulsationsauswerteeinrichtung 19 , in particular of their computers 29 , The control device 20 but also the pulsation level PL of the monitoring bands via the analog output 26 and even the evaluation of the trigger signal according to 2 carry out.

The control device 21 can over a network connection 31 and via a network controller 32 with the calculator 29 the Pulsationsauswerteeinrichtung 19 communicate. The control device 21 For example, the Pulsationsüberwachung, using the Pulsationsauswerteeinrichtung 19 is carried out, configure, visualize and / or store. Furthermore, the control device 21 here with the display and / or diagnostic system 22 coupled, for example via the Internet 33 What, for example, an evaluation of the long-term operation of the gas turbine 1 allows. In particular, this evaluation for several different gas turbines 1 , which can be distributed globally, take place centrally.

1

gas turbine

2

compressor

3

combustion chamber

4

turbine

5

sensors

6

amplifier

7

diagram

8th

diagram

9

Fourier transformer

10

diagram

11

RMS rectifier

12

Monitoring frequency band

13

diagram

14

diagram

15

intersection

16

protection action

17

control system

18

Pulsationsmesseinrichtung

19

Pulsationsauswerteeinrichtung

20

control device

21

control device

22

Display- and / or diagnostic system

23

galvanic separator

24

Low Pass Filter

25

analog input

26

analog output

27

Digital input

28

Digital output

29

computer

30

galvanic decoupled connection

31

Network Connection

32

Network Controller

33

Internet

P

pulsation

t

Time

PZS

Pulsation-time signal

f

frequency

PFS

Pulsation frequency signal

PL

pulsation

PL _max

Pulsationsmaximalwert

PLZS

Pulsation-time signal

PL _limit

level limit

AZ

trigger counter

AZ _limit

Release Tough Stand

AZS

Trigger counter-time signal

RZ

Reset counter

RZ _limit

Reset count

RZS

Reset counter-time signal

SAZ

Protective action status

RZ _SAZ

certain meter reading of the reset counter

t ₀ -t ₁₆

certain timings

Claims (17)

Method for protecting a gas turbine ( 1 ) against damage by pressure pulsations (P), - at least in a monitoring frequency band ( 12 ) the pulsations (P) a pulsation level (PL) is monitored with regard to the occurrence of at least one predetermined triggering condition, - in which at the occurrence of the at least one triggering condition a predetermined protective action (PL) 16 ), in which the at least one triggering condition has a tripping strategy which operates with a tripping counter (AZ) and with a reset counter (RZ), in which the tripping counter (AZ) determines the time (t) during which the respective pulsation level (PL) is above a predetermined level _limit (PL _limit ), summed up to the respective preceding counter reading, - at which the triggering condition occurs and the predetermined protection action ( 16 ) is started as soon as the trigger counter (AZ) reaches a predetermined trigger count (AZ _limit ), - in which the reset counter (RZ) the time (t) during which the respective pulsation level (PL) is not above the level _limit (PL _limit ) , in each case summed up to a count set to zero, - in which the count of the trigger counter (AZ) is set to zero as soon as the reset counter (RZ) reaches a predetermined reset count (RZ _limit ). Method according to claim 1, characterized in that the protective action ( 16 ) and the count of the trigger counter (AZ) is reset to zero if the reset counter (RZ) during the protective action ( 16 ) reaches a predetermined count (RZ _SAZ ). A method according to claim 2, characterized in that said predetermined count (RZ _SAZ ) is less than the reset count (RZ _limit ). Method according to one of claims 1 to 3, characterized in that - during operation of the gas turbine ( 1 ) occurring pressure pulsations (P) are measured, - that from the measured pressure pulsations (P) a pulsation time signal (PZS) is generated, - that the pulsation time signal (PZS) in a pulsation frequency signal (PFS ) is transformed from the pulsation frequency signal (PFS) for at least one predetermined monitoring frequency band (PFS). 12 ) the pulsation level (PL) is determined. A method according to claim 4, characterized in that the pulsation level (PL) by summation or integration and / or by averaging the pulsation values (P) in the respective monitoring frequency band ( 12 ) is determined. A method according to claim 4, characterized in that the pulsation level (PL) by the maximum pulsation value (P) in the respective monitoring frequency band ( 12 ) is formed. Method according to Claim 6, characterized in that the monitoring frequency band ( 12 ) is tracked at a frequency shift of the maximum pulsation value (P) the maximum pulsation value (P), so that the maximum pulsation value (P) within the monitoring frequency band ( 12 ) remains. Method according to one of claims 4 to 7, characterized in that the respective monitoring frequency band ( 12 ) is determined so that exactly one prior art critical pulsation (P) occurs at its occurrence with its pulsation frequency in this monitoring frequency band (P) ( 12 ) lies. Method according to one of claims 4 to 8, characterized from the pulsation level (PL) a pulsation level time signal (PLZS) is generated, which monitors with regard to the at least one triggering condition becomes. Method according to claim 9, characterized in that that the pulsation level time signal (PLZS) by averaging is processed. Method according to one of claims 4 to 10, characterized in that the transformation of the pulsation time signal (PZS) into the pulsation frequency signal (PFS) by means of a numerical-mathematical transformation, in particular by means of a fast Fourier transformation ( FFT) or by means of a Discrete Fourier Transformation (DFT), is carried out. Method according to one of claims 4 to 11, characterized - that at Occurrence of a pulsation (P) is checked whether this pulsation (P) is a harmonic of a pulsation (P) is from a lower frequency range, - and that the associated one Pulsation level (PL) only then monitored if it is in the associated Pulsation (P) is not such a harmonic. Method according to one of claims 4 to 12, characterized in that the occurrence of the at least one triggering condition for each monitoring frequency band ( 12 ) is monitored separately. Control system for a gas turbine ( 1 ), - with a pulsation measuring device ( 18 ), which by means of a suitable sensor ( 5 ) which during operation of the gas turbine ( 1 ) measures occurring pressure pulsations (P) and generates a correlated pulsation time signal (PZS), - with a Pulsationsauswerteeinrichtung ( 19 ), which transforms the pulsation time signal (PZS) into a pulsation frequency signal (PFS), from the pulsation frequency signal (PFS) for at least one predetermined monitoring frequency band (PFS). 12 ) determines a pulsation level (PL), monitors it with regard to the occurrence of at least one predetermined triggering condition and generates a triggering signal when the at least one triggering condition occurs, with a control device ( 20 ), which, given the triggering signal, has a predetermined protective action ( 16 ). Control system according to claim 14, characterized in that for the transmission of the pulsation time signal (PZS) between the Pulsationsmesseinrichtung ( 18 ) and the pulsation evaluation device ( 19 ) a galvanic decoupled connection ( 30 ) is arranged. Control system according to claim 14 or 15, characterized in that a control device ( 21 ) is provided via a network connection ( 31 ) to the pulsation evaluation device ( 19 ) and the one configuration of the pulsation evaluation device ( 19 ) and / or visualizes and / or stores the pulsation monitoring. Control system according to claim 16, characterized in that the control device ( 21 ) to a display and / or diagnostic system ( 22 ) connected to the evaluation of the long-term operation of the gas turbine ( 1 ) serves.