My query is regarding TNR calculation. Can anybody provide the formula for TNR calculation (NOT FSRN) during Straight Droop Control, Constant Settable Droop Control, Preselect Load Control.

Actually When I analysed the formula for FSRN which is always given in this forum, I realised that TNR calculation is always missing and which is the most important factor. Due to this I'm curious to know the calculation that how the TNR is calculated in different modes.

Moreover in the straight speed droop control mode, is there any curve like (load vs valve lift) applied after FSRN? or calculated FSRN value directly goes to open the governing control valve?

Regards,
SSV

 

The answers to all these questions are in the sequencing or application code for any GE-design heavy duty gas turbine.

By following the signals through the sequencing, and applying some knowledge of relay ladder-style documentation, one should easily be able to determine how each of these signals are determined.

Another good source of information is the Speedtronic Control Specification drawing. Sometimes, there are very useful tidbits of information in there that just make everything so clear. (That's not always true, but it's a good place to look for additional information.)

TNR doesn't change depending on whether the unit is in part load or exhaust temperature control, including Pre-selected Load Control.

L70R and L70L drive TNR. If you follow these signals forwards and backwards through the sequencing or application code, you will be able to see how TNR is derived.

In short, TNR is a value that is driven up or down depending on whether the action is trying to increase or decrease the turbine power output. The rate at which it increases or decreases can also change, depending on the action initiating the increase or decrease. (Some changes, for example, occur as a result of combustion trouble, and as such, the rate of change is faster than for an operator-initiated change.)

Please have a look at the documentation for your unit, and if you have specific questions, we can try to answer them here.

 

Hello,

As a matter of fact, I don't have GE GT logic and that's why I asked these questions, but of course I have to go through the logic and trace back to know about TNR calculations, that is fine. I actually learned from control.com regarding GE GT controls.

But if you can reply the last sentence of my previous thread i.e. regarding Is there any function curve (like MW vs valve lift) after final FSRN value or FSRN value is directly going to control the governing valve. (OK, FSRN calculation takes care of no load and full load values of valve opening (in FSKRN2 & FSKRN1) but still is there any curve?)

Secondly, in droop speed control, when operator raise or lower the load, it means he/she is raising or lowering the speed, so Is there any function curve (like %MW vs speed differential or droop curve) in between raise/lower load and speed setpoint/reference ? or load raise/lower command is directly raising/lowering speed reference ?

Thirdly, In preselect droop control, IS there any Proportiona-Integral control loop to control the load ? and if not how is the calculation?( if you can tell without directing me towards the logic/documentation)

Fourthly, I am working on retrofit of GE steam turbine (from MARK III control to Ovation DCS). So are these gas turbine droop control fundamentals applicable to steam turbine also ? (obviously not exhaust temp. control) I am asking only for droop speed control / preselect load control.

Thanx! in advance

Best Regards
SSV