We have two gas turbine of 25MW each running in parallel. Both turbine share 26MW plant load (13MW load each). Due to some problem, SRV upstream pressure of one gas turbine decreased from 18 to 16KG/cm2 recently. This gas turbine is operated on DROOP mode.
As load increased on this Gas Turbine from 13 to 14MW SRV opened up to 1.5" (total = 1.9 notches). The gas turbine did not take any further load beyond 14MW.
FSR = 30%
P2 Pressure = 15.75 to 15.54KG/cm2

1)My question is that if the other gas turbine trips this gas turbine normally shifts to Peak Load and takes 18MW load.
Will it happen now as on a slight load change SRV tends to open fully?? how it will take more load?? Is there any part to be played by GCV which has FSR 30%.

2)What if we Change the Set point of Pressure controller situated at the upstream of SRV from 18.5 to 19.5 kg/cm2 to compensate pressure depletion at strainer. Will it improve gas turbines ability to take more load?

 

Firstly, you need to get an understanding of the SRV & GCV function and how they inter-relate to each other. Search the forum, there is lot's in here regarding SRV & GCV operation, & study your P&IDs and control specs.

If your supply gas pressure is falling, exactly what has happened will happen. Check your specs. and see what your minimum supply gas pressure should be and get it reset to that value.

Simply, your machine ran out of fuel, the supply gas pressure dropped, the SRV opened to try and maintain P2 pressure until it was wide open and could do no more (P1 was less than required P2), P3 then was too low to support the load required.