HK1167010B - Stabilizing a gas turbine engine via incremental tuning - Google Patents

Description

Stabilizing a gas turbine engine by step-wise adjustment

Cross reference to related applications

This application claims priority from U.S. provisional application No. 61/181253 filed on 26/5/2009 and U.S. non-provisional application 12/786189 filed on 24/5/2010, both of which are incorporated herein by reference in their entirety.

Technical Field

The present invention relates generally to automatically tuning a gas turbine engine. More specifically, a process and system are identified for providing a control system to automatically adjust a gas turbine engine by incrementally (incementally) adjusting one or more fuel flow splits (fuel flow split) within a combustion chamber or incrementally adjusting a gas fuel temperature.

Background

Gas turbine engines operate to produce mechanical work or thrust. In particular, land-based gas turbine engines typically have a generator coupled thereto for the purpose of generating electrical power. The shaft of the gas turbine engine is coupled to an electrical generator. The mechanical energy of the shaft is used to drive a generator to supply at least the power grid. The generator communicates with one or more elements of the power grid through the main breaker. When the main breaker is closed, current can flow from the generator to the power grid when there is a need for power. The flow of current (drawing) from the generator causes a load to be applied to the gas turbine. This load is essentially the impedance applied to the generator that the gas turbine must overcome to maintain the electrical output of the generator.

Control systems are increasingly being used to regulate the operation of gas turbine engines. In operation, the control system receives a plurality of indications that convey current operating conditions of the gas turbine engine (including pressure, temperature, fuel flow rate, and engine frequency). In response, the control system adjusts the input to the gas turbine engine to change the performance of the gas turbine engine based on the plurality of indications according to a look-up table encoded into a memory of the control system. Over time, this performance may fall outside of the preferred operating range due to mechanical degradation of the gas turbine engine or changes in operating conditions such as ambient temperature or fuel composition. For example, a gas turbine engine may begin operating beyond regulated emissions limits. As such, multiple manual adjustments are required to update the control system. Manual tuning is labor intensive and may cause commercial related inefficiencies such as extended downtime of the gas turbine engine, and operator error in the tuning process. In addition, because there are specific time windows where manual adjustments may not be available (e.g., high dynamics events), but performing adjustment operations would be beneficial to guard against potential damage to the hardware, making automatic adjustments during those time windows would capture those benefits of typical manual adjustment misses.

Disclosure of Invention

In accordance with the present invention, a new method of monitoring the operating conditions of a gas turbine engine and responding to conditions that exceed a predetermined upper limit is provided. First, various engine operating conditions may be monitored. As an example, these operating conditions may include, but are not limited to, emissions and combustor dynamics modes such as Lean Blow Out (LBO), Cold Tone (CT), Hot Tone (HT), and screech. When the monitored operating condition exceeds one or more predetermined upper limits, the engine parameter is altered to adjust this condition to be within the upper limits, thereby tuning the gas turbine engine.

More specifically, pressure fluctuations (also referred to as combustion dynamics) may be detected in each combustion chamber of the gas turbine engine (e.g., using a pressure sensor). Next, a fourier transform may be applied to the pressure signal to convert the pressure signal to a format of amplitude versus frequency. The maximum amplitude within a predetermined frequency band within a time frame may be compared to a predetermined upper pressure limit or alarm level limit. With the comparison, when it is ascertained that the upper pressure limit is exceeded by the maximum magnitude, appropriate corrective action is taken. In some instances, the appropriate action is performed manually. In another example, the appropriate action is implemented by the control system. For example, the control system may initiate a process that alters one or more fuel flow splits within a fuel circuit of the combustor. In an exemplary embodiment, one fuel flow split is altered one at a time by a predefined step amount. As described herein, the term "predefined step amount" is not meant to be construed as a limitation, but may encompass a wide range of adjustments to the fuel flow split. In one example, the predefined step amount is a uniform (uniform) adjustment amount that is consistently applied to one or more fuel stream splits. In another example, the predefined amount is an adjustment variance that is altered across fuel flow splits or across adjustments for a particular fuel flow split. By altering the fuel flow split in this manner, the fuel-air mixing within the combustion chamber is altered, thus affecting the combustion signature. The pressure fluctuations are modified as the combustion characteristics are affected.

This modified combustion dynamics amplitude, once stabilized, is again compared to the predetermined upper limit to verify whether the adjusted fuel flow split has moved the amplitude within an acceptable range. If the amplitude remains above the predetermined upper limit, the fuel flow split is again adjusted by the predefined step amount, and the process is repeated recursively as needed. Advantageously, the fuel flow split is changed consistently and uniformly with the same predetermined step size, thereby saving processing time to calculate a customized value of the step size each time the predetermined upper limit is exceeded.

Accordingly, in an exemplary embodiment of an auto-tuning process, a control system for monitoring and controlling a gas turbine engine is provided. This control system generally manages most processes, involves auto-tuning the combustion chamber, and may be referred to as an auto-tuning controller. First, the process includes monitoring combustion dynamics and emissions of the combustion chamber for a plurality of conditions. When it is determined that one or more conditions exceed a predetermined upper limit, a fuel flow split for the fuel circuit is adjusted by a predetermined amount. The control system or auto-tuning controller continues to monitor combustion dynamics and dynamically adjust the fuel flow stream by a predetermined amount until the combustion dynamics fall below a predetermined upper limit.

Further, in an alternative embodiment of the auto-tuning process, the gas turbine engine is monitored and automatically tuned based on data retrieved from the monitoring. Typically, autoregulation involves stepping the fuel flow split up or down in order to maintain combustion dynamics and emissions within preferred operating ranges, or above/below limits. In particular, the alternative process first includes detecting a pressure signal in the combustion chamber during the monitoring step. An algorithm is applied to the detected pressure signal either subsequent to or concurrent with the monitoring step. In one example, the application algorithm involves performing a fourier transform on the pressure signal to convert the pressure signal into frequency-based data or spectrum. The amplitude of the frequency-based data is compared to a predetermined upper limit (amplitude) for different known conditions. If it is determined that the amplitude of the frequency-based data exceeds its respective predetermined upper limit, a step-wise adjustment in the fuel flow split is made. In one example, the step-wise adjustment is a change in fuel flow split that is performed at a fixed and predetermined amount. This step-wise adjustment may increase or decrease the fuel flow split depending on the frequency band being examined and/or the type of fuel circuit being adjusted. This alternative process is repeated recursively until the frequency-based data indicates that the gas turbine engine is operating within the proposed range.

In one example, if the replacement process has been recursively repeated many times such that the fuel flow split of a particular fuel circuit has reached a maximum allowable value, the second fuel flow split affecting the second fuel circuit may be adjusted by a predefined fixed amount. If the measured frequency-based data indicates that the gas turbine engine is operating within the recommended range, the replacement process is ended. Otherwise, the second fuel flow split is recursively adjusted by the same predefined fixed amount until the amplitude of the frequency-based data moves to an acceptable level, or a maximum allowable value of the second fuel flow split is reached. In embodiments, the predefined fixed amount may vary based on which fuel flow split is being monitored, the number of steps that have been applied to the adjustment of a particular fuel flow split, or other conditions or parameters that affect the adjustment of the fuel flow split.

In another example, if the replacement process has been recursively repeated many times such that the fuel flow split for a particular fuel circuit has reached a maximum allowable value, the stepwise adjustment of the fuel flow split is stopped. When the step-wise adjustment is stopped, the adjustment of the gas temperature may be invoked to bring the operation of the gas turbine engine within a particular performance range. If the adjustment of the gas temperature does not properly adjust the gas turbine engine, an alarm indication is communicated to an operator. This alert indication may be communicated to a console, pager, mobile device, or another technique suitable for receiving electronic messages and relaying notifications to an operator. The operator will be given the option of stepping the fuel gas temperature or stepping the engine firing temperature. If this option is selected, the auto-tuning controller will incrementally adjust any of these parameters and repeat the process until the cell meets (in compliance) or reaches a maximum limit. If this process is not successful, an alarm indication may alert an operator that the automatic adjustment has failed to bring the operation of the gas turbine engine within a recommended range, and that manual adjustments to the combustor or control system are recommended before the adjustment is completed.

Additional advantages and features of the invention will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the invention. The present invention will now be described with particular reference to the accompanying drawings.

Drawings

The invention is described in detail below with reference to the attached drawing figures, wherein:

FIG. 1 is a block diagram of an exemplary tuning environment suitable for use with embodiments of the present invention;

FIG. 2 is an exemplary graph depicting recommended fuel flow split adjustments for fuel rich conditions, according to an embodiment of the invention;

FIG. 3 is an exemplary graph depicting a recommended fuel flow split adjustment for a combustor equipped with two injection ports, in accordance with an embodiment of the present invention;

FIG. 4 is a flow diagram of an overall method for employing an auto-tuning controller to implement a tuning process that includes collecting measurements from a combustion chamber and alerting fuel flow splits based on the measurements, according to an embodiment of the present invention.

Detailed Description

The subject matter of the present invention is described with specificity herein to meet statutory requirements. However, the description itself is not intended to limit the scope of this patent. Rather, the inventors have contemplated that the claimed subject matter might also be embodied in other ways, to include different components, combinations of components, steps, or combinations of steps similar to the ones described in this document, in conjunction with other present or future technologies.

As will be appreciated by those skilled in the art, embodiments of the invention may be realized, inter alia, as: a method, system, or computer program product. Rather, the embodiments may take the form of a hardware embodiment, a software embodiment, or an embodiment combining software and hardware. In one embodiment, the invention takes the form of a computer program product comprising computer-useable instructions embodied on one or more computer-readable media.

Computer-readable media include both volatile and nonvolatile media, removable and non-removable media, and contemplates media readable by a database, a switch, and various other network devices. Network switches, routers, and related components are conventional in nature, as are the components with which they communicate. By way of example, and not limitation, computer readable media may comprise computer storage media and communication media.

Computer storage media or machine-readable media include media implemented in any method or technology for storage of information. Examples of stored information include computer-usable instructions, data structures, program modules, and other data representations. Computer storage media includes, but is not limited to, RAM, ROM, EEPROM, flash memory or other memory technology, CD-ROM, Digital Versatile Disks (DVD), holographic media, or other optical disk storage, magnetic cassettes, magnetic tape, magnetic disk storage, and other magnetic storage devices. These storage components may store data momentarily, temporarily, or permanently.

Communication media typically embodies computer usable instructions including data structures and program modules in a modulated data signal. The term "modulated data signal" means a propagated signal with one or more of its characteristics set or changed in such a manner as to encode information in the signal. Exemplary modulated data signals include carrier waves or other transport mechanisms. Communication media includes any information delivery media. By way of example, and not limitation, communication media includes wired media such as a wired network or direct-wired connection, and wireless media such as acoustic, infrared, radio, microwave, spread-spectrum, and other wireless media technologies. Combinations of the above are included within the scope of computer-readable media.

As described above, embodiments of the present invention generally relate to automatically tuning a gas turbine engine. Referring to FIG. 1, a gas turbine engine 110 housing a plurality of combustors 115 is depicted. Generally, for purposes of discussion, the Gas Turbine (GT) engine 110 may include any low emission combustion chamber. In one example, the low emission combustion chambers may be arranged in a can-annular configuration with respect to the GT engine 110. One type of GT engine (e.g., a heavy-duty GT engine) may typically be equipped with (but is not limited to) 6 to 18 individual combustion chambers, each of which is equipped with a combustion chamber liner, an end plate, and a sleeve. Another type of GT engine (e.g., a light-duty GT engine) may be equipped with fewer combustion chambers. Thus, based on this type of GT engine, there may be several different fuel circuits for operating the GT engine 110. Further, there may be a respective fuel circuit corresponding to each of the plurality of combustion chambers 115 attached to the GT engine 110. Thus, it is to be understood and appreciated that: the auto-tune controller 150 and the tuning process performed thereby (see reference numeral 400 of fig. 4) may be applied to any number of configurations of GT engines, and the type of GT engine described below should not be construed as limiting the scope of the invention.

As discussed above, the plurality of combustors 115 (e.g., low emission combustors) may be prone to elevated levels of pressure fluctuations within the combustor basket. This pressure fluctuation is referred to as "combustion dynamics". Combustion dynamics alone may have a significant impact on the integrity and life of the plurality of combustion chambers 115, ultimately leading to catastrophic failure. These combustion dynamics may be moderated by adjusting the fuel flow split of the combustor gas flow between sets of nozzles within the plurality of combustors 115. Generally, the fuel flow split is typically adjusted for each of the plurality of combustors 115, and thus the combustors (burners) are adjusted similarly, as opposed to at individual burner levels. These various "fuel flow splits" are intermittently adjusted to ensure that acceptable levels of combustion dynamics (typically low levels) are maintained while at the same time acceptable emission levels are elevated. The acceptable emission level relates to the amount of pollutants generated by the GT engine 110. The schedule (schedule) governing the fuel flow split of each fuel circuit is typically hard coded into the control system (not shown) of the GT engine 110. In one example, the schedules may be a function of, among other things, a turbine inlet reference Temperature (TIRF) or a reference amount of load on the GT engine 10.

Several parameters will affect combustion dynamics over time. In particular, changes in environmental conditions and/or variations in gas composition and/or normal wear may deteriorate the operation of the GT engine. This degradation results in regular "re-tuning" of the combustor to maintain combustion dynamics and emissions within acceptable limits. As discussed herein, the auto-tune control system or auto-tune controller 150 of fig. 1 is used to assess the state of the GT engine 110 and the plurality of combustion chambers 115 based on parameters such as combustion dynamics, airflow, fuel flow, emissions, and pressure profiles. Based on these parameters, sufficient fuel flow diversion is achieved by incrementally adjusting fuel flow diversion until an alarm has been cleared, wherein the alarm is set when the magnitude of the pressure pulse is detected to exceed a predetermined upper limit. Accordingly, embodiments of the present invention are directed to an auto-tuning controller 150, and associated tuning process, that enables automatic tuning of combustion dynamics and emissions using small, consistent, step-wise changes in fuel flow splits.

The overall tuning process performed by the auto-tuning controller 150 may include one or more steps described immediately below. First, various configurations of pressure signals of the plurality of combustion chambers 115 are monitored and recorded. These recorded pressure signals are subjected to a fourier transform, wherein the pressure signals are converted into a format or spectrum of amplitude versus frequency data. The amplitude and frequency are then monitored and, for each predefined frequency band, the amplitude is compared with a predetermined upper limit. The predetermined upper limit is generally defined in terms of pounds per square inch (psi) of the predefined frequency band. However, in other examples, the predetermined upper limit may be expressed in other terms or units, where other types are measuring the performance of the combustion chamber 115 with a device (e.g., an accelerometer). If it is determined for a predetermined frequency band that one or more of the frequency-based magnitudes exceeds their respective predetermined upper limits, the auto-tuning controller 150 first determines which fuel flow split to adjust and second alerts the fuel flow split associated with the particular frequency band. This adjustment of the fuel flow split is performed in a predefined amount.

Once the fuel flow split adjustment is made, the process is repeated. That is, if the dynamic pressure amplitude is above a predetermined upper limit, the following steps are repeated: the amplitudes are monitored for a plurality of predetermined frequency bands and compared to predetermined upper limits and predetermined fuel flow splits are adjusted. Specifically, the same predetermined adjustment is made to the fuel flow split when the dynamic pressure amplitude is ascertained to be above the predetermined upper limit. The adjustment process is repeated as necessary until the dynamic pressure amplitude falls below a predetermined upper limit, or until no further adjustment of the fuel flow split is possible.

If the first fuel flow split cannot be further adjusted, the second fuel flow split is adjusted by a second predefined rate and the adjustment process is repeated, or an alarm indication is issued to the operator. With respect to adjusting the second fuel flow split, the adjustment process repeats until the dynamic pressure amplitude falls below the predetermined upper limit or no further adjustment of the second fuel split is possible. If the second fuel flow split cannot be further adjusted, a third or more fuel flow split is adjusted.

While the schemes for iteratively adjusting fuel flow splits in sequence have just been described above, those of ordinary skill in the art will understand and appreciate that other types of suitable schemes for adjusting fuel flow splits may be used, and embodiments of the present invention are not limited to those schemes that focus on one fuel flow split at a time. For example, one embodiment of the tuning scheme may iteratively adjust the first fuel flow split by a predefined step amount until the dynamic pressure amplitude falls below a predetermined upper limit, or until a certain number of iterations is reached (whichever occurs first). If a certain number of iterations is reached, the adjustment scheme causes the second fuel flow split to be iteratively adjusted by another predefined step amount until the dynamic pressure amplitude falls below the predetermined upper limit, or until another certain number of iterations is reached (whichever occurs first). If another specified number of iterations is reached, the modulation scheme returns to the first fuel flow split. Specifically, the adjustment scheme causes the first fuel flow split to be iteratively adjusted again by the predefined step amount until the dynamic pressure amplitude falls below the predetermined upper limit, or until a third particular number of iterations is reached (whichever occurs first). The modulation scheme may then return to the second fuel flow split or be diverted to a third fuel flow split for regulation purposes.

With reference to fig. 1 and 4, an exemplary embodiment of the adjustment process will now be described in detail. First, FIG. 1 illustrates an exemplary regulatory environment 100 suitable for use in embodiments of the present invention. The exemplary tuning environment 100 includes an auto-tuning controller 150, a computing device 140, and a GT engine 110. The automatic tuning controller 100 comprises a data storage 135 and a processing unit 130, said processing unit 130 supporting the execution of the acquisition component 131, the processing component 132 and the adjustment component 133. Generally, processing unit 130 is implemented as some form of computing unit (e.g., a central processing unit, microprocessor, etc.) that supports the operation of components 131, 132, and 133 running thereon. As used herein, the term "processing unit" generally refers to a dedicated computing device having processing power and storage memory that supports operating software under which software, applications, and computer programs run. In one example, the processing unit 130 is configured with tangible hardware elements or machines that are integrated into or operatively coupled to a computer. In another example, the processing unit may include a processor (not shown) coupled to a computer-readable medium (discussed above). Generally, a computer-readable medium stores, at least temporarily, a plurality of computer software components executable by a processor. As used herein, the term "processor" is not intended to be limiting and may encompass any element of a processing unit that acts in a computational capacity. With such capabilities, the processor may be configured as a tangible article of manufacture that processes instructions. In an exemplary embodiment, processing may involve fetching, decoding/interpreting, executing, and writing back instructions (e.g., reconstructing physical gestures by presenting animations of motion patterns).

In addition, the automatic adjustment controller 100 is provided with a data memory 135. Generally, the data storage 135 is configured to store information associated with the tuning process or data generated when monitoring the GT engine 100. In various embodiments, such information includes, without limitation, measurement data (e.g., measurements 121, 122, 123, and 124) provided by sensors 120 coupled to GT engine 110. Additionally, the data store 135 may be configured to be searchable for suitable access to the stored information. For example, the data store 135 may be searched for a schedule to determine which fuel flow split step when comparing the measured dynamic pressure amplitude to a corresponding predetermined upper limit. It will be understood and appreciated that: the information stored in the data storage 135 may be configurable and may include any information related to the adjustment process. The content and quantity of such information is not intended to limit the scope of embodiments of the present invention in any way.

In an embodiment, the auto-tune controller 100 will record a look-up table (e.g., using the data store 135 of FIG. 1). These look-up tables may include various information related to the operating conditions of the GT engine and the combustion chambers attached thereto. By way of example, the lookup table may include an operating curve having a recommended tolerance band (tolerance band) that defines an outer limit (outer limit) of valid operation. When performing a process of automatically tuning the GT engine, the auto-tuning controller may be automatically reprogrammed to record aspects of the tuning process in the operating profile. That is, the operating curve in the lookup table is modified to reflect events during and caused by the adjustment process. Advantageously, the modified operating curve may be accessed during the next adjustment procedure, thus making each subsequent adjustment more efficient (e.g., reducing the number of fuel flow adjustment steps required to bring the condition below a predetermined upper limit). In this way, a look-up table (e.g., an operation matrix) can be automatically developed by stepwise adjustment of one parameter at a time. Because the step adjustments are stored in the operating curve, the auto-tune controller learns the optimal tuning performance for any particular operating system. This greatly reduces the amount of adjustment required, which would be beneficial to units where the stabilization points could be on scarce Automatic Grid Control (AGC), or units that experience sudden cyclic changes in fuel properties or environmental conditions.

In some embodiments, if the adjustment by adjusting the fuel flow split does not mitigate emissions or dynamic alarms, an incremental bias (incemental bias) may be provided to adjust the fuel temperature according to the optimum out-of-compliance split set point identified for each of the above sections. However, if incrementally biasing fuel temperature is not an option-due to lack or limited fuel temperature handling capability-and the unit remains in the alert mode, a request may be issued to allow adjustment of the firing profile of the GT device. If the operator request is granted, a stepped firing temperature offset is provided to the existing unit firing profile at the point of optimum non-compliance described in the section above.

With continued reference to the look-up table stored on the auto-adjustment controller 100, a variation of the look-up table configuration will now be described. In one example, a number of look-up tables are provided that plot the split versus TIRF or load. Each of these look-up tables relates to a plurality of combinations of ambient temperature and gas parameters. The "gas parameter" is a characteristic of the gas composition and properties and can be implemented as a relative value compared to a calibrated initial value. The trim adjustment is performed at a stable TIRF or load. Whenever a step-wise offset adjustment is required because an alarm level or emission level is exceeded, the algorithm first determines in which ambient temperature and gas parameter family the unit is operating and then determines which fuel split to change and in which direction. Second, the bias is expected to step (up or down) and the current TIRF or load is recorded. The algorithm then determines which table will be modified based on the recorded ambient temperature and gas parameters. Once defined, the algorithm determines which points in the graph of split versus TIRF contain (blacket) the current value for the TIRF. When these two points are identified, the bias values for the two points are modified (up or down) in steps and the steps are stored in the correct look-up table.

Additionally, the exemplary tuning environment 100 includes a computing device 140 operatively coupled to a presentation device 145 for displaying a User Interface (UI) display 155 that alerts an operator to the inability to automatically tune the GT engine 100. The computing device 140 shown in fig. 1 may take the form of various types of computing devices. By way of example only and not limitation, computing device 145 may be a personal computer, desktop computer, laptop computer, handheld device, consumer electronic device (e.g., pager), handheld device (e.g., personal digital assistant), various servers, and the like. It should be noted, however, that the present invention is not limited to implementation on such computing devices, but may be implemented on any of a variety of different types of computing devices within the scope of embodiments of the present invention.

Referring to FIG. 4, the tuning process 200 will now be discussed in accordance with the exemplary tuning environment 100 of FIG. 1. Generally, FIG. 4 is a flow diagram of an overall method 400 for implementing an adjustment process that includes collecting measurements from a plurality of combustors 115 and altering fuel flow splits based on the measurements, using the auto-adjustment controller 150 of FIG. 1, in accordance with an embodiment of the present invention. First, the overall method 400 includes monitoring data indicative of combustion dynamics of the GT engine 100. In one embodiment, the combustion dynamics 122 are measured for each of the plurality of combustion chambers 115 using a sensor 120 (e.g., a pressure sensor) that communicates measurement data to the acquisition assembly 131. In another embodiment, the sensor 120 communicates emissions 122 detected from the GT engine 100. In still other embodiments, the measurement data collected from the GT engine 110 may include, but is not limited to, GT parameters 123 and gas intake pipe pressure (gas manifold pressure) 124.

In some examples, the data collected from the GT engine 100 is normalized (normaize). For example, the sensor 120 may be configured as a pressure transducer that detects pressure fluctuations in each of the plurality of combustion chambers 115 and reports these fluctuations as combustion dynamics 122. The fluctuations may be measured over a period of time and sent to the acquisition component 131 in the form of a rolling average of pressure variability.

Step 430 of the overall method 430 pertains to passing the measured data through a fourier transform or another suitable algorithm to convert the data into a magnitude versus frequency format (using the processing component 132 of fig. 1). This amplitude versus frequency format may take on various configurations (such as a graph, chart, or matrix), and is referred to hereinafter as a "spectrum. In one example, when the format of amplitude versus frequency presents a configuration of a matrix, the matrix may include the following value categories: combustion chamber identification, frequency and amplitude.

In an embodiment, the spectrum may be divided by a frequency range, or may be discretized into a plurality of frequency bands, where each frequency band has its own predetermined upper limit in amplitude. The spectrum may be discretized into any number of frequency bands. In one example, the frequency spectrum is discretized into 4-6 frequency bands or windows, each frequency band representing a different parameter, based on the type of GT engine 100 being adjusted. In operation, when a predetermined upper limit (i.e., alarm level limit) for a particular frequency band is exceeded, the schedule instructs the auto-tuning controller 150 which fuel flow split to change and in which direction (up or down) to make adjustments. Typically, the appropriate fuel flow split and the appropriate manner of adjustment to be changed is selected based on the type of measured data being processed (e.g., combustor dynamics or emission levels) and the nature of the measured data being processed (e.g., combustor dynamics quality (tone), type of emissions such as NOx or Co).

In step 440, maximum dynamic pressure amplitudes are identified within each frequency band. The maximum dynamic pressure amplitude may be determined by selecting the maximum dynamic pressure amplitude for each type of measured data (combustion dynamics 122) within one or more frequency bands. Both the predetermined upper limit (i.e., alarm level limit) and the maximum dynamic pressure amplitude obtained from each frequency band are measured in pounds per square inch (psi).

The identified maximum kinetic pressure amplitude is compared to an appropriate predetermined upper limit, as depicted in step 450. (there is no particular priority to compare or handle outlier (outlier) maximum frequencies.) this predetermined upper limit may be based on the type of measured data being evaluated and/or the fuel circuit being adjusted. When compared, a determination is made whether the maximum dynamic pressure amplitude exceeds a predetermined upper limit, as depicted at step 460. If the maximum dynamic pressure amplitude does not exceed the predetermined upper limit such that the GT engine 100 is operating within the recommended range for the particular measured data, the adjustment process moves to another condition. That is, the adjustment process continues to monitor and evaluate another set of measured data, as depicted at step 470. By way of illustration, the dynamic pressure amplitude is monitored only in a series of frequency bins (bins). Other parameters are not a function of the frequency window, but are still subject to maximum regulatory limitations.

However, if the maximum dynamic pressure amplitude does not exceed the predetermined upper limit, the fuel flow split is selected for adjustment. This is indicated at step 480 of fig. 4. As discussed above, the appropriate fuel flow split is selected by the schedule, as discussed more fully below with reference to fig. 2 and 3. This selected fuel flow split is then incrementally adjusted by a pre-specified amount, as depicted at step 490. The step-wise adjustment of the fuel flow split may be accomplished by the adjustment assembly 133 of fig. 1 communicating a step-wise offset adjustment 160 to at least one of the plurality of combustion chambers 115 mounted to the GT engine 100. In one embodiment, an automatic valve on the combustor 115 adjusts the fuel flow split to the subject fuel circuit in response to recognizing the incoming stepped bias adjustment 160.

This predetermined amount is typically based on the test experience and the combustor identification (as provided by the matrix). In one example, the predefined stepwise adjustment amount is a 0.25% adjustment of the fuel flow split between the injection ports. Thus, the fuel flow distribution pattern through the injection points is modified by stepping the fuel flow split up or down a pre-specified amount. However, even with varying fuel flow splits, the total fuel flow to the fuel circuit remains generally constant.

When applying the stepped bias adjustment 160, the auto-tune controller 150 waits a period of time before acquiring and processing data extracted from the GT engine 100. This is depicted in step 500 of fig. 4. Waiting for this period of time ensures that the GT engine 100 is stable before checking to determine whether the adjusted fuel flow split is sufficient to adjust the GT engine 100. In embodiments, the period of time to wait between adjustments may vary based on the parameter being processed or the type of data being measured. For example, the period of time required to stabilize combustion dynamics may be less than the period of time required to stabilize emissions.

At step 510, a determination is made to ascertain whether the maximum number of steps has been reached. If the maximum number of steps that can adjust the fuel flow split is not reached, the process is allowed to iterate. Thus, if the comparison step 450 indicates that further stepwise adjustment is required, the fuel flow split may be adjusted at least once more. However, if the maximum number of steps that can adjust the fuel flow split is not reached, another fuel flow split may be adjusted (as determined by a schedule), or a warning sent to the operator. This is depicted in step 520. In one embodiment, the alert indicator 180 is sent by the processing component 132 to the computing device 140. In response to the alert, the operator may take action to manually adjust the GT engine 100 or contact a technician to service the GT engine 100.

In some embodiments, sending an alert to the operator is the first action taken, as indicated by the schedule. That is, if the measured data for a particular parameter exceeds a corresponding predetermined upper limit while the data is being processed by fourier transformation, the first action taken is to notify the operator of the deviation, as opposed to incrementally adjusting the fuel flow split.

Another embodiment allows the operator to allow the auto-tune controller 150 to incrementally adjust the fuel gas temperature and/or the ignition temperature to achieve compliant operation.

Turning now to FIG. 2, an exemplary graph 200 or schedule depicting recommended fuel flow split adjustments for fuel rich conditions is provided in accordance with an embodiment of the present invention. As illustrated, the graph 200 includes an indication 210 of the type of fuel consumed by the adjusted GT engine. In addition, the chart includes a row 220 that lists the monitored conditions. In this exemplary graph 220, there are four conditions that are monitored, which are parameters A through D. Although four conditions are monitored in this example, the number of conditions monitored should not be construed as limiting as any number of conditions may be observed for automatically adjusting the GT engine. In general, the parameters a-D may represent specific conditions measured using pressure transducers, emission testing equipment, accelerometers, and other items capable of monitoring the operation of the GT engine. As an example, parameter a may represent Lean Blowout (LBO), parameter B221 may represent Cold Turn (CT), parameter C may represent Hot Turn (HT), and parameter D may represent nitrogen oxide (NOx). Thus, in this example, parameters a to C relate to pressure data, while parameter D relates to gas composition. Typically, the gas composition is determined by monitoring the concentration levels of emissions (e.g., CO and NOx). An adjustment process with step-wise adjustment (similar to that described above) may be used in conjunction with conditions involving emissions.

Each of the parameters a to D is automatically monitored during the adjustment process. In addition, the data monitored during the adjustment process is processed by a fourier transform to determine the maximum amplitude for each condition. If any of these conditions' maximum magnitudes exceed or fall below the respective predetermined limits mapped to each parameter A through D, respectively, then act 230 is performed.

As an example, if the maximum amplitude of parameter B221 (e.g., CT condition) exceeds a separate predetermined upper limit mapped to parameter B221, acts 231, 232, and 233 are performed based on order 250. Specifically, if the maximum dynamic pressure amplitude of parameter B221 exceeds a predetermined upper limit, the split 2232 is first increased by a step amount, as indicated by the sequence 250. Then, the split 1231 is decreased when the split 2232 is recursively increased by a step amount until a maximum number of adjustments of the fuel flow split is reached. Next, if the adjusted split 1231 is not valid, it is performed on split 3233. Finally, if the adjusted split 3233 is ineffective to reduce the maximum frequency amplitude below a predetermined upper limit, an alert is sent to the operator. As will be appreciated in the related art, the above exemplary methods are merely examples of processes for automatically adjusting a particular engine, such as a 7FA engine, and there will be different methods for automatically adjusting fuel flow splits, including different monitored parameters and changes, for other engines.

While a single configuration of a schedule (e.g., chart 200) to select which action to take in view of exceeding a predetermined upper limit has been described, those of ordinary skill in the art will understand and appreciate that: other types of suitable schedules that provide an organized hierarchy of actions may be used, and embodiments of the invention are not limited to the conditions and actions of the schedules described herein. Additionally, it should be noted that auto-tuning controllers may be used with a variety of combustion systems. Thus, the present invention is not limited to only three fuel split adjustments. The exact amount of fuel nozzles and fuel flow splits may vary depending on the combustion chamber configuration and type of GT engine being tuned. Thus, the number of adjustment points may be greater or less than the number depicted in the present disclosure for different combustion systems without departing from the essence of the present disclosure.

Further, the graph 200 depicts adjustments to fuel flow splits in response to multiple frequency bands for various monitored conditions. If the plurality of frequencies exceed their respective predetermined upper limits, the auto-tune controller does not prioritize or prioritize to determine which frequency is handled first. However, in other examples, the auto-tune controller 150 of fig. 1 utilizes some priority policy to make decisions as to in which order to handle frequencies.

Referring to FIG. 3, an exemplary graph 300 depicting a recommended fuel flow split adjustment 320 for a combustor equipped with two injection ports is shown, in accordance with an embodiment of the present invention. Because only two injection ports are provided, there is only one fuel flow split that can be adjusted to distribute fuel between the provided injection ports. Further, two conditions 310 of the adjusted GT engine are measured in this example. These conditions 310 are represented by parameters a and B. If either parameter A or B exceeds the corresponding predetermined upper limit, the schedule indicates which of the fuel flow split adjustments 320 to take. If adjusting the prescribed fuel flow split the maximum recommended number of times does not bring the GT engine into the normal operating range, the next step involves sending an alert to the operator or automatically placing a call to the technician.

When comparing the automatic adjustment with the current adjustment process, various benefits resulting from the automatic adjustment may be recognized. That is, because the adjustment process of the present invention can be automatically performed, the disadvantages of manual adjustment are overcome. For example, automatic adjustments may be performed quickly and often, which will substantially prevent degradation that may have occurred prior to manual adjustments. In addition, frequent adjustments reduce excess pollutants/promote lower emissions while improving engine life.

The present invention has been described in relation to particular embodiments, which are intended in all respects to be illustrative rather than restrictive. Alternative embodiments will become apparent to those of ordinary skill in the art to which the present invention pertains without departing from its scope.

From the foregoing, it will be seen that this invention is one well adapted to attain all the ends and objects set forth above, together with other advantages which are obvious and inherent to the system and method. It will be understood that certain features and subcombinations are of utility and may be employed without reference to other features and subcombinations. This is contemplated by and is within the scope of the claims.

Claims (14)

1. A method for automatically tuning a combustor of a gas turbine engine, the method comprising: monitoring one or more operating conditions of the gas turbine engine; determining whether the one or more operating conditions have exceeded a threshold; and when the threshold is exceeded, the processing that occurs includes a) comparing the identification of the one or more operating conditions that have exceeded the threshold to a schedule, b) selecting a fuel flow split from the schedule to effect the adjustment based in part on the comparison, and c) adjusting the selected fuel flow split by a predefined step amount, wherein adjusting the fuel flow split by the predefined step amount includes consistently applying a uniform adjustment amount to the fuel flow split, and wherein the fuel flow split governs the portion of the total fuel flow that flows to each fuel nozzle of the fuel circuit of the combustor.

2. The method of claim 1, wherein monitoring one or more operating conditions of the gas turbine engine comprises: recording pressure pulses of the combustion chamber; and passing the recorded pressure pulses through a fourier transform to form frequency readings associated with the recorded pressure pulses.

3. The method of claim 2, wherein determining whether the one or more operating conditions have exceeded a threshold comprises: comparing the maximum amplitude of the pressure pulse to a predetermined upper limit associated with at least one combustion chamber mode; and detecting that the maximum amplitude exceeds at least one of the predetermined upper limits.

4. The method of claim 3, further comprising: verifying that the adjustment to the fuel flow split reduces the one or more operating conditions below the threshold.

5. The method of claim 4, wherein verifying comprises: pausing for a period of time to allow operating conditions of the gas turbine engine to stabilize; recording the pressure pulse of the combustion chamber; and determining whether a subsequent maximum amplitude resulting from the re-recorded pressure pulse exceeds at least one of the predetermined upper limits.

6. The method of claim 5, further comprising: implementing another adjustment to the selected fuel flow split by the predefined step amount when it is determined that the subsequent maximum amplitude exceeds at least one of the predetermined upper limits.

7. The method of claim 5, further comprising: when it is determined that the subsequent maximum amplitude falls within the acceptable operating range, the adjustment of the selected fuel flow split is stopped.

8. The method of claim 1, wherein the uniform adjustment amount consistently applied to the selected fuel flow split is based on an identification of a currently adjusted fuel flow split.

9. The method of claim 1, wherein the one or more operating conditions comprise an emission of a gas turbine engine.

10. The method of claim 1, wherein the one or more operating conditions include combustor dynamics including lean blowout, cold turn, hot turn, and screech.

11. The method of claim 1, wherein adjusting the selected fuel flow split by the predefined step amount comprises: determining whether to increase or decrease the selected fuel flow split as a function of one or more operating conditions that exceed the threshold or as a function of the type of the fuel flow split selected for adjustment.

12. A method for automatically stabilizing combustion chamber dynamics or emissions of a gas turbine by employing a tuning process, the method comprising: providing a gas turbine engine comprising one or more combustors each equipped with a fuel flow split for governing a portion of a total fuel flow to each fuel nozzle of a fuel circuit of the combustor; and employing an automatic tuning controller for performing the tuning process, the tuning process comprising: measuring one or more parameters from the gas turbine engine, wherein the one or more parameters represent at least one of pressure data or gas composition; obtaining amplitudes for the one or more measured parameters, respectively; determining whether the amplitude exceeds a predefined limit mapped to the one or more measured parameters; accessing a schedule to select an appropriate said fuel flow split to alter when said predefined limit is exceeded; and adjusting the selected fuel flow split by a predefined step amount by applying a uniform adjustment amount to the selected fuel flow split.

13. The method of claim 12, wherein accessing a schedule to select an appropriate fuel flow split to modify comprises: identifying a disorder parameter from the one or more measured parameters, wherein the resulting magnitude of the disorder parameter exceeds a predefined limit mapped thereto; and selecting a first fuel flow split to alter when the schedule is checked with respect to the imbalance parameter, and wherein the adjusting process further comprises: determining, using the schedule, a step size for adjusting the first fuel flow split; and determining a direction of adjustment of the first fuel flow split using the schedule.

14. A control system for monitoring and controlling a gas turbine engine, the control system configured to perform a method for automatically tuning a gas turbine engine, the method comprising: monitoring one or more operating conditions of the gas turbine engine; determining whether the one or more operating conditions have exceeded a threshold; and adjusting the fuel flow split by a predefined step amount when the threshold is exceeded, wherein adjusting the fuel flow split by the predefined step amount includes applying a uniform adjustment amount to the fuel flow split, and wherein the fuel flow split dominates the portion of the total fuel flow that flows to each fuel nozzle of the fuel circuit of the combustor.