Can any one please describe exactly in detail about FSR TNR TNH and their interrelations?

 

Nothing like an easy question to start the day....

Droop speed control (which is how GE heavy-duty combustion turbines are controlled between generator breaker closure and CPD-biased exhaust temperature control) involves comparing a turbine speed setpoint (TNR, expressed in percent of rated speed) to actual turbine speed (TNH, expressed in percent) and using any error between the two to control the amount of fuel admitted to the turbine. The error between TNR and TNH is used to produce FSRN, or Speed Control FSR.

[NOTE: When the generator breaker is open, any increase in TNR WILL cause turbine speed to increase; any decrease in TNR will cause turbine speed to decrease.]

FSR, Fuel Stroke Reference, is expressed in percent--percent of maximum expected fuel flow-rate. For units running on natural gas fuel, the Gas Control Valve opening is calibrated such that the 100% effective opening (which is NOT always the full mechanical stroke of the valve/actuator) of the valve corresponds to maximum expected gas fuel flow-rate. For units running on liquid fuels such as distillate (diesel) or heavy fuel oil (residual- or crude oil), the Liquid Fuel Flow Divider pulse-rate feedback is used to measure and control fuel flow-rate.

Several different Fuel Stroke References are always being calculated at all time: FSRN (Speed Control FSR), FSRT (CPD-biased Exhaust Temperature Control), FSRACC (Acceleration Control FSR), FSRSU (Start-up Control FSR), and FSRSD (Shutdown Control FSR). All these FSR values are "fed" into a Minimum Value "gate" which selects the lowest of the values and that signal becomes FSR.

Assuming a new and clean compressor and turbine, rated atmospheric conditions, and a typical factory control system configuration, a four (4) percent increase in TNR (turbine speed reference) results in rated power output of the turbine-generator. In other words, when TNR is approximately 104%, the unit should be producing rated power output and operating on CPD-biased exhaust temperature control.

When an operator is "loading" or "unloading" a GE heavy-duty combustion turbine-generator what he/she is really doing is increasing or decreasing the turbine speed reference (TNR). As the error signal between TNR and TNH increases or decreases, FSRN increases or decreases, and the amount of fuel admitted to the turbine (FSR) increases or decreases.

[TNH stands for Turbine Speed-High Pressure Shaft. Some GE heavy-duty combustion turbines can have two shafts: a high-speed shaft and a low-speed shaft, hence the differentiation.]

 

<p>OK! I try to make a long story short,

<p>TNR = Turbine Speed Reference<br>
TNH = Turbine Speed Measure (High Pressure Shaft)<br>
FSR = Fuel Stroke Reference

<p>Let look at the schematic of feed back control loop.
<pre>
+-------------+ +--------+
+-----+ error | | FSR | |speed
TNR--->| sum |------>| FUEL |----->|TURBINE |-----
+ +-----+ |CONTROL LOOP | | | |
^ - +-------------+ +--------+ |
|TNH |
| |
+----------------------------------------------
</pre>

<p>FSR is the output to servo valve (Fuel Gas or Fuel Oil Valve, depends on
your application).

<p>FSR is the output selected from fuel control loop, the output from
this loop is the minimum selection among:
<pre>
- FSRSU = FSR Start Up
- FSRACC = FSR for Acceleration
- FSRN = FSR for Speed Control
- FSRT = FSR for Temperature Control
and there are two more FSRs which I can't recall from the
top of my head now. Anyone can help?
</pre>
<p>The error between setpoint (TNR) and measure (TNH) is feeding to 'fuel
control loop'

<p>Don't be surprise with term 'high pressure' for TNH because in some
application like 'Aero Derivative Engine' it has two shafts, the speed at
Gas Generator is called 'TNH' (High Pressure) and speed at Power Turbine
is called 'TNL' (Low Pressure).

<p>Hope this will help.

<p>Regards,

<p>PRAN SAMMSANTI

 

I can find FSRDW in the min value gate. What is the function of it? our gas turbine is GE frame 6b controlled with mark v.

 

This must be some custom sequencing; approximately 20 Mk V requisitions were reviewed and none of them had FSRDW anywhere in the sequencing.

You should be able to work backwards from the Min. Value Gate input to see how the signal is developed. The guess, from the signal name, is that it's some kind of load limit based on megawatt feedback--but that's just a SWAG (Scientific Wild-A$$ed Guess).

markvguy

 

The other two are FSRSYN and FSRMAN.

><p>OK! I try to make a long story short,
>
><p>TNR = Turbine Speed Reference<br>
>TNH = Turbine Speed Measure (High Pressure Shaft)<br>
>FSR = Fuel Stroke Reference

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