# Droop Speed in 9E GTs

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#### OMAR

Hi all ,

Our plant consists of:

a. 4 GTs 9E and CONSTANT SETTABLE DROOP SPEED/LOAD CONTROL .
b. control system is MVIE .

1. what is the signal name of Droop speed which is equal 4%?

2. How can i know from the logic the load ramp rate (MW/Min)?

3. In case Droop Speed is acting with grid frequency change is there fast ramp rate, if existing how much?

Thanks

#### mthines

1. what is the signal name of Droop speed which is equal 4%?

The control constant is typically DWKDG that is used for the macro CON_SET_DRP. This constant scales the droop response according to the ISO rating of your turbine in its location.

Turbine Iso Rating/Droop number(usually 4 or 5)=DWKDG

2. How can i know from the logic the load ramp rate (MW/Min)?

This depends on what ramp rate you are referring to. There are many different ramp rates used depending on what control is being executed, like external load control, local mw control, synchronizing, high exhaust spread etc. The rates are not set as mw/min but rather the % change of TNR per second. You can look in the logic in the area SPDLDREF. It depends on who wrote your logic as to what macros and logic are in use.

3. In case Droop Speed is acting with grid frequency change is there fast ramp rate, if existing how much?

If grid frequency changes there is no ramp rate. Turbine speed(TNH) is compared to speed reference(TNR). If either changes then fuel scheduling changes immediately.

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Hi MikeVI,

I was just about to respond to this when I saw your response. I agree with 2 & 3. To the best of my knowledge

DWKDG = % Droop / Unit base load MW

so for a frame 9E machine in Indian subcontinent conditions about 120MW

DWKDG = 4/120 = 0.033 ( assuming 4% droop)

It will be be something very similar at Omar's site. if its supplied by BHEL it will be typically set to 0.035.

#### OMAR01

Thanks for reply to MIKEVI for helpful and valuable information, regarding to DWKDG = 0.0341035 . And Droop = 4% . But please I want know if possible, the MW ramp rate signal at local MW control. Thanks also to Pc load letter for your nice participation.

#### mthines

You will need to search your logic for signals like L83JD1-9. These signals will typically be connected to an array that selected different rates of change for TNR. You will need to find your digital inputs for the governor raise/lower, then follow them to find which L83JD signal they are attached, and finally find the value associated with it for the TNR rate of change.