Raise and lower turbine speed during load

M

Thread Starter

Mr

Hi All,

We have frame 6 Gas turbine controlled by Mark VI TMR Control system.

is it possible to raise and lower turbine speed when 52G closed and unit loaded with preselected load? and if it is possible. How can we do it?
 
Go to the load control screen on the HMI and use the RAISE or LOWER "pushbutton." This will take the load control out of preselected mode and leave it in manual mode - the FSR should remain steady, the load will change as ambient temperature changes.

Alternatively, you can RAISE of LOWER the preselected load setpoint, in which case the load will hold steady at the new setpoint, as long as it remains below the base load temperature limit and (possibly) above any minimum limit imposed by DLN.
 
Hi,

Why is it necessary to change speed during loaded operation?

Are you able to change turbine speed when 52G is closed and Pre-Select Load is not in operation? If the answer is yes, how do you change speed during loaded operation?

How large is the grid (load) the unit is operating in parallel with? Is it a small island (cement plant or refinery), or a utility system with hundreds or thousands of customers (homes, businesses, factories, etc.)?
 
otised,

Methinks he wanted to know how to change the turbine speed while in Pre-Selected Load....

Otherwise, the answer was completely correct.
 
OOPS! I read your original posting too quickly. I thought you meant speed/load setpoint, but now I see you said "speed."

If your 52G is closed to a grid, you are unlikely to be able to change speed. If you are running isolated from the grid then you can change the speed with the RAISE and LOWER commands.

If your grid is really small, such that your frame 6 generator is a significant part of the total generating capacity, then you might be able to change speed with the RAISE and LOWER commands.
Why are you trying to change speed?
 
Thanks a lot for the replys. actually the unit is connected to the plant and the load of plant about 15MW and there is grid supply. some times we lost the grid supply and the unit carrying the load of plant.
We want to back to normal.

It means with the load We want to raise and lower the speed of gas turbine to match the grid for synch, check and connecting the grid supply again
 
First of all, it should not be possible to operate a machine and a load independent of other machines (in "island" mode) in Pre-Select Load Mode. The Speedtronic should be in Isochronous Governor Mode and that will adjust the fuel to maintain frequency regardless of the load. You can't tell a machine that's isolated from other machines to produce 20 MW if the load it's connected to is only 12.6 MW. Well, you can, but the frequency will go way above desired.....

Second, when you want to resynchronize to the grid what most plants do is switch from Isochronous mode to Droop mode, and then adjust the speed frequency using the RAISE- and LOWER SPD/LOAD buttons or switches to adjust the frequency as necessary to re-close the breaker with the grid. Then when the unit is re-synch'ed to the grid it can be put in Pre-Select Load Control in Droop Governor Mode.

It is also possible to re-synchronize in Isochronous Governor Mode using the same RAISE- and LOWER SPD/LOAD buttons/switches, but when the breaker closes the unit must automatically switch to Droop Governor Mode or there will usually be large load swings and/or load instability until the operator switches to Droop Governor Mode. (That's why it's better to switch to Droop at the time of re-synchronization. At least for most GE-design heavy duty gas turbines using Speedtronic turbine control systems.)

Hope this helps!
 
When you are with grid, not possible to change "Speed" of gas turbine. When isolate from grid and only connected with complex load you can raise/lower "Speed" by changing TNRI set point in the band of 97 % to 101 %.
 
>... you can raise/lower "Speed" by changing TNRI set point in
> the band of 97 % to 101 %.

TNRI is the Isochronous Turbine Speed Control Reference, and it's changed using the same RAISE- and LOWER SPD/LOAD buttons/switches as when operating in Droop Governor Mode.

But, if one changes the Isoch speed setpoint when re-synchronizing one still has to be careful that the governor is switched from Isoch to Droop when the unit is re-synchronized to the grid, or there will almost certainly be load swings until the governor change is made.
 
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