Dear CSA,

May I know how FSRT is calculated? How's the FSRT value comes from? I know when FSRT value is higher, gas control valve can open more but when FSRT value is lower, the gas control valve will open less which in turn giving less power output.

 

Dear FAI,

I suspect that CSA may have a longer and more descriptive answer for you, but in case he is busy I will try give you a quick answer. Also you may want to search the archives of control.com since the subject of FSR should yield lots of results.

FSR, Fuel Stroke Reference is the reference value that determines the placement of the gas control valves, and in the end turbine power output. FSR is the minimum selected choice of values for FSRN (speed), FSRSU (start-up), FSRACC (acceleration), FSRT (temperature) and several others that are used to control fuel inlet to the turbine.

Typically when running the turbine at part load the FSR value is using FSRN, adding fuel to maintain a fixed speed. As you continue to add fuel to raise turbine output, exhaust temperature and firing temperature will rise. The firing temperature used on most GE heavy duty gas turbines is TTRF. This is the calculated temperature of the exhaust entering the 1st stage nozzles. For each given turbine there is a maximum allowable temperature for this hardware to be operated at reliably.

So at some point the TTRF temperature hits the limit programmed in logic where fuel must be held or reduced to control this temperature. This is the limit of FSRT. As mentioned TTRF is a calculated value which is arrived at by measuring several values including but not limited to exhaust temperature, compressor pressure ratio etc.

FSRT will move around based mainly on ambient conditions. Simply put the turbine needs air and fuel to make power. More fuel, more power. But also more air, more power. More air(mass) can be produced with cooler air(density) and an efficient(clean) compressor, or a compressor turning faster(frequency). This last item is one to note. During times of low system frequency the compressor will slow down, which means less air, which means less output, typically just when you need more output!

Anyway thats my quick description of FSRT. I would suggest you look at your logic if possible (you did not mention which control system you have) and follow signals of FSR, FSRT etc. There is not one simple block to look at for understanding FSRT, but many different areas to study and understand.

 

Dear FAI,

For Fr-6 machines,

FSRT calculation -

FSRT = FSR + (TTRXB-TTXM)* 0.0360 deg.cent

TTRXB - Base load ref temperature

As the difference between TTRXB & TTXM reduces, the turbine load increases ultimately with the difference being zero and machine on base load