9FA gas turbine

Hello

When the 9 fa gas turbine reach the fsnl , the gas turbine still increase the speed over 3000 rpm , and it's imossible to synchronize in the grid

What can i check to solve this issue

Thanks
 
Hello,

Can you tell us :
-Controls systems type/model,
-Are the permissives for sync are all ok prior to synchronize...
-Is the Generator stator voltage is matching grid frequency ..prior to sychronize
-Any Alarm annuciated on any control sytem ??


With more accurate informations that you can provide , the best we can help on this issue.


ControlsGuy25.
 
the control systems are markVIe /MarckVIes
all the permissive are ok
yes the generator voltage is ok
No alarm
in the startup TNR was 95% instead 100.3%

Thanks
 
Is this a new control system commissioning? Or an older installation that’s having new problems? Never mind the permissives on the HMI screen, go into the Workstation, open the MKVIe SW in Toolbox, and look at the parameters writing to the L25P point. Make sure those values make sense.

After that, look at the TNRV1 droop speed reference block.
 
mirak,

When did the problem begin? Is this a new/newer unit that has always had trouble synchronizing? Are you trying to synchronize to a large utility grid? Is the utility grid stable (meaning is the frequency stable)? Are you trying to synchronize to a captive power island (isolated from a larger grid)?

What Master Control Mode is the unit operating in when it reaches FSNL (AUTO; REMOTE; etc.)?

What Governor Mode is the unit operating in when it reaches FSNL (Droop Speed Control or Isochronous Speed Control)?

What do the operators do when the unit reaches FSNL? Do they try to adjust the turbine speed? How do they try to adjust the turbine speed?


How high does the turbine speed increase when it exceeds FSNL?

On the Synchronizing Display there are several dots (usually arranged vertically on the left side of the display). For synchronizing to occur, the dots should all be green. What dots are green and what dots are NOT green? (It's possible use a cell phone camera to capture a pictures of display and then attach them to your replies--CLEAR photos would be a GREAT help).

Finally, specifcally what Process Alarms are active at the time the unit reaches FSNL? If there is a Process Alarm indicating the presence of one or more Diagnostic Alarms, use ToolboxST to find the I/O Packs with Diagnostic Alarms, write them down, and list them here in a reply.

Presuming there are few Process Alarms, and even fewer Diagnostic Alarms--and that the alarms are really and truly unrelated to the speed problem, we need to understand when this problem started, how the unit is being operated (Master Control Mode; Governor Mode), what the synchronizing permissive lights are doing when the unit should be at FSNL. Under normal circumstances, when the unit reaches FSNL, the operator should select the desired synchronizing mode (AUTO or MANUAL); let's presume AUTO. At this time, the Mark* should begin the process of speed (frequency) matching (matching the generator speed/frequency to the grid frequency) and also voltage matching (matching the generator terminal voltage to the grid voltage). There should be NO external speed signals acting on the Mark* (such as from a PMS (Power Management System) or DCS); the Mark* should be using it's inputs from the turbine speed sensors, the generator potential transformers and the grid potential transformers to adjust speed (frequency) and voltage, and then, at the appropriate time send signals to close the generator breaker. Once the generator breaker closes, the operator should then put the HMI synchronizing mode in OFF (if it doesn't automatically switch to off--which it should).

If you see that when the synchronizing mode is set to AUTO that the RAISE SPEED/LOAD target on the HMI is orange or flashing orange and the operators are not clicking on the target with the mouse, and the speed continues to increase above approximately 100.3% TNH, then it's very likely that some external signal is trying to increase the turbine speed (or load--if it thinks the generator breaker is closed). So, we need to understand a LOT more about how the unit is being operated, when this problem started and what is being done to synchronize the unit with the problem you have barely described. Above is what should happen on a typical machine. If there are unusual external controls you have not told us about, or unusual operating conditions or modes you have not told us about there's not much ,ore we can add until you provide more information.
 
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