GE Frame 7 Turbine VIGV issue

Good Day, There is an issue with our GE frame 7 gas turbine. The VIGV goes fully open at (84 deg) at 66 MW's. The machine is rated for 75 MW's . We are in the tropics so on a hot day we normally get 71 MW's (at 84degF) and 74 MW's (77degF) at night. What cause the VIGV to go fully open at 66MW's ? Please help. Thanks
 
Aleem ALI,

You really didn't tell exactly how your turbine is being operated. Is it operating in Simple Cycle mode, exhausting to atmosphere (possibly through a bypass stack if there's an HRSG (Heat Recovery Steam Generator)? Or is exhausting into an HRSG to make steam for a steam turbine and/or some process plant nearby, in which case it would probably be operating in Combined Cycle Mode (also known as IGV Exhaust Temperature Control mode)?

What are ALL the Process Alarms currently annunciated on the machine?

What are ALL the Diagnostic Alarms currently annunciated on the machine?

What is the value of axial compressor discharge pressure (signal name CPD)?

What is the actual exhaust temperature (signal name TTXM)?

What is the exhaust temperature reference (signal name TTRX)?

What is the IGV reference (signal name CSRGV)?

What is the IGV LVDT feedback (signal name CSGV)?

What are the conditions of the two axial compressor bleed valves (signal names L33CB1O and L33CB2O--those are the capital letter O, not zeroes)?

Were the IGV LVDTs "calibrated" recently? If so, how recently? (I AM NOT suggesting the IGV LVDTs need calibrating--not at all!!! I'm simply asking if someone felt the need to calibrate the IGVs (for whatever reason), and if so how recently were they "calibrated" and what was the reason for the need to calibrate the IGV LVDTs?)

What is the value of the Turbine Speed Reference (signal name TNR)?

What is the frequency of the grid the turbine-generator is synchronized to? Is it stable or fluctuating? What is the frequency when you are unable to generate the load you think you should be generating?

The list of Process- and Diagnostic Alarms will tell us a lot, and so will the values of the signals requested. Please provide the values of the requested signals during a time when the unit is perceived NOT to be producing normal power output.

Finally, does the unit have any kind of axial compressor inlet air cooling--such as evaporative coolers, or chillers, or foggers? If so, are they running when this perceived problem is occurring?
 
Curious_One,

Glad to be of help (always)!

I think we all understand that this GE turbine operation stuff can be a little intimidating and overwhelming, especially in the beginning. And, I think we all know that GE's documentation and system descriptions can be a little ... lacking, to say the least.

So, I try to keep an even keel when we get questions like this. It's like when I assisted the GE PAC (Power Answer Center) with questions and problems from the field. I'm being deadly serious when I say we would regularly receive PAC Cases with the following information: "It's broken. How do I fix it?" Or, "It's not working. What do I do?" And, when we would ask for data, we would get the nastiest responses and reviews--sometimes so nasty the Op's Managers in the PAC would call and ask why (and some of them were not joking--they hadn't read the Case and just assumed we had not given good information. Some (more than you would believe) wouldn't even have information that related to the problem at all--they were just passing along information some operator or plant manager thought was relevant, but wasn't. And, these people writing the PAC Cases--they were "trained" GE field service people (most of them). It was sad, and got sadder. And is even sadder now.

I know some of these operators (and I think a LOT of the questions like this on Control.com come from operators--not all, but most) have had no formal training of any kind. And probably never will get any formal training (because as soon as the Company pays for training, that person is going to leave with their certificate of completion to work somewhere else for a dollar a day more than they're making now). It's a sad situation. They don't know that Alarm Management IS their primary job! They think--because that's what they've been told--that as long as the unit doesn't trip, just ignore any alarms (there are so many of them anyway). And, if it does trip, just try to restart it as soon as possible and if it starts and synchs and loads, well, then, it was probably a "fake alarm" anyway, right?

I just ask the questions. Sometimes we get answers--but we almost NEVER get the full list of responses we ask for. And quite often, the requested information is overwhelming and they don't even know how to look up the information and values, or they don't have access to Toolbox or ToolboxST. In the beginning, people asking these questions just believe that EVERY Frame 7 is exactly like every other Frame 7--because they're all called Frame 7s, so they must all be alike right? And, every problem on a Frame 7 is like every problem on a Frame 7--because they're all on a Frame 7. Never mind some have hydrogen-cooled generators; others have air-cooled generators. Some have hydraulic ratchets for COOLDOWN; some have slow roll. Some burn crude oil; some burn residual; some burn coke gas; some burn high-sulfur distillate. Some have a Mark II, some have a Mark IV, some have a Mark V, some have a Mark VI, some have a PLC for a turbine control system. But, they're all called Frame 7s--so they must all be alike! (Are all Peugeot 206s alike, I wonder?)

One just tries to do what one can do--and hope for the best.

Thanks for your support, too, Curious_One. It is much appreciated--by me, at a minimum, and by many others, too, I'm sure!
 
They think--because that's what they've been told--that as long as the unit doesn't trip, just ignore any alarms (there are so many of them anyway). And, if it does trip, just try to restart it as soon as possible and if it starts and synchs and loads, well, then, it was probably a "fake alarm" anyway, right?

That statement made me laugh into tears. Decades ago: when I was developing Cimplicity screens. I was training a technician about the Cimplicity visibility property. We started with a smiley face, I showed him how to use a button to make the smiley face happy or sad. WE laughed into tears.

I applied this to the generator breaker close and open. From that moment on, the operators said " Press the Start button and wait for the Smiley face".
 
All of this is off topic... but without even a basic understanding of the OPs setup...

It's like when I assisted the GE PAC (Power Answer Center) with questions and problems from the field.
I put in more time than I like to think about handling PAC cases when I worked at GE O&G. I think that’s one reason I’ve been hanging out here more often the last few years. It’s almost nostalgic.

I was training a technician about the Cimplicity visibility property. We started with a smiley face, I showed him how to use a button to make the smiley face happy or sad. WE laughed into tears
Working through some custom alarms and alarm rationalization with an operations manager, he wanted a specific alarm to “flash red and yellow like the ****ing McDonalds sign so the operators can’t acknowledge it and hope it goes away.” I was in a mood, so I also attached the “I’m lovin’ it” soundbite from a McDonald’s commercial to the alarm. The HMI engineer and I thought was funny. We laughed and moved on to the next part of the project. I forgot about it until the customer witness test. The customer (luckily) thought it was the best thing he’d seen all day and made me leave it in.
 
Yes, we're getting off topic, but we ain't hearin' nuthin' from the original poster, either....

:unsure:

Things that make you go, "Hmmmmmmmm...."

Anyway, these are good stories! Everyone needs a little levity once in a while, eh?
 
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