Automated extended turndown of a gas turbine engine combined with incremental tuning to maintain emissions and dynamics
View Patent ↗An auto-tune controller and tuning process implemented thereby for measuring and tuning the combustion dynamics and emissions of a GT engine, relative to predetermined upper limits, are provided. Initially, the tuning process includes monitoring the combustion dynamics of a plurality of combustors and emissions for a plurality of conditions. Upon determination that one or more of the conditions exceeds a predetermined upper limit, a fuel flow split to a fuel circuit on all of the combustors on the engine is adjusted by a predetermined amount. The control system continues to monitor the combustion dynamics and to recursively adjust the fuel flow split by the predetermined amount until the combustion dynamics and/or emissions are operating within a prescribed range of the GT engine. Additionally, a method of automated extended turndown of a GT engine to find a minimum load is provided.
1. A computerized method, implemented by a processing unit, for automated extended turndown of a combustor of a gas turbine (GT) engine, the method comprising:
receiving an input to perform the automated extended turndown on the GT engine;
monitoring one or more turndown criteria of the GT engine to determine if all of the one or more turndown criteria are met;
upon determining that all of the one or more turndown criteria are met, temporarily reducing a transfer-out turbine reference temperature (TTRF) if a difference between a current TTRF and the transfer-out TTRF of the GT engine is less than a configured amount;
sending a signal to reduce a load on the GT engine by a specified amount;
reducing the load on the GT engine by the specified amount based on the signal;
during and after the load has been reduced, monitoring the one or more turndown criteria to determine if any of the one or more turndown criteria are not met;
upon determining that at least one of the one or more turndown criteria is not met after the load has been reduced, tuning the load a selected number of times until the at least one turndown criteria is not met the selected number of times; and
upon the at least one turndown criteria not being met the selected number of times, storing a minimum load turndown TTRF where all turndown criteria have been met for a selected compressor inlet temperature (CTIM).
2. The method of claim 1 , wherein upon determining if any of the one or more turndown criteria are met, again reducing the load by the specified amount or a modified specified amount.
3. The method of claim 1 , wherein the selected CTIM comprises one or more CTIM ranges.
4. The method of claim 1 , further comprising calculating the transfer-out TTRF, the transfer-out TTRF calculated by adding a first selected temperature margin to the minimum load turndown TTRF.
5. The method of claim 4 , wherein the first selected temperature margin is selected based on a safety margin.
6. The method of claim 4 , further comprising calculating an operating TTRF, the operating TTRF calculated by adding a second selected temperature margin to the minimum load turndown TTRF.
7. The method of claim 6 , wherein the second selected temperature margin is greater than the first selected temperature margin.
8. The method of claim 1 , wherein the processing unit is configured to transmit the minimum load turndown TTRF.
9. The method of claim 6 , wherein the processing unit is configured to check restriction of tuning knobs to a user configured setting.
10. The method of claim 1 , wherein the selected number of times comprises the exhaustion of a tuning margin.
11. The method of claim 6 , wherein the processing unit is configured to generate an alarm to recheck the minimum load turndown TTRF when the CTIM changes from a first CTIM range to a second CTIM range.
12. The method of claim 1 , wherein the turndown criteria comprise at least one of:
a nitrogen-oxide (NOx) level; a combustor dynamics mode;
an average carbon monoxide (CO) level; or fuel circuit splits.
13. A system for automated extended turndown, the system comprising:
a gas turbine (GT) engine including one or more combustors that are each provided with a first minimum turbine reference temperature (TTRF), a first transfer-out TTRF, and a first operating TTRF;
an auto-tuning controller for carrying out an automated extended turndown process comprising:
(a) receiving an input to the perform the automated extended turndown process;
(b) monitoring one or more turndown criteria to determine if the one or more turndown criteria are all met;
(c) upon determining that the one or more turndown criteria are all met, temporarily reducing the first transfer-out TTRF to a second transfer-out TTRF if a difference between a current TTRF and the first transfer-out TTRF is less than a configured amount;
(d) sending a signal to reduce a load on the GT engine by a specified amount;
(e) reducing the load on the GT engine by the specified amount based on the signal;
(f) during and after the load has been reduced, monitoring the one or more turndown criteria to determine if the any of the one or more turndown criteria is not met;
(g) upon determining that any of the one or more turndown criteria is not met during or after the load has been reduced, tuning the load a selected number of times until the turndown criteria that is not met is not met the selected number of times; and
(h) upon the turndown criteria that is not met being not met the selected number of times, storing a second minimum TTRF where all turndown criteria are met for a selected CTIM.
14. The system of claim 13 , wherein the system further comprises a user input device.
15. The system of claim 14 , wherein the system further comprises a user display device configured to receive and display information related to the monitored criteria.
16. The system of claim 13 , further comprising a load controller configured to receive commands from the auto-tune controller to increase or decrease a load on the GT engine.
17. The system of claim 13 , further comprising calculating a new transfer-out TTRF by adding a first selected temperature margin to the second minimum TTRF.
18. The system of claim 17 , further comprising calculating a new operating TTRF by adding a second selected temperature margin to the second minimum TTRF.
19. The system of claim 13 , further comprising:
checking turndown criteria to determine if a tuning limit is reached; and
determining a new higher minimum TTRF.
20. The system of claim 13 , wherein the turndown criteria comprise at least one of:
a nitrogen-oxide (NOx) level; a combustor dynamics mode;
an average carbon monoxide (CO) level; or fuel circuit splits.
21. One or more non-transitory computer readable media that, when invoked by computer executable instructions, perform a method for automated extended turndown of a gas turbine (GT) engine, the method comprising:
monitoring one or more turndown criteria of the GT engine to determine if all of the one or more turndown criteria are met;
upon determining that all of the one or more turndown criteria are met, temporarily reducing a transfer-out turbine reference temperature (TTRF) if a difference between a current TTRF and the transfer-out TTRF is less than a configured amount;
sending a signal to reduce a load on the GT engine by a specified amount;
reducing the load on the GT engine by the specified amount based on the signal;
during and after the load has been reduced, monitoring the one or more turndown criteria to determine if any of the one or more turndown criteria is not met;
upon determining that at least one of the one or more turndown criteria is not met after the load has been reduced, tuning the load a selected number of times until the at least one turndown criteria that is not met is not met the selected number of times; and
upon the at least one turndown criteria that is not met being not met the selected number of times, storing a minimum load turndown TTRF where all of the one or more turndown criteria are met for a selected compressor inlet temperature (CTIM).