S
during peak time our GT which is in 120MW suddenly decreases to nearly 100MW when frequency increases from 49.75 to 50.5hz.
can anyone explain in detail about this?
can anyone explain in detail about this?
B
Bruce Durdle
When frequency increases, the sped of the alternator and all connected machinery increases as well.
Your turbine governor will react to an increase in speed by reducing fuel flow, and therefore reducing load. I would suggest that your power reduction is actually a bit less as from the figures given the droop is 7/5 % which is a bit high. If the frequency excursion is short-lived, the meter may not be responding fast enough to indicate the full extent of the transient.
Bruce.
Your turbine governor will react to an increase in speed by reducing fuel flow, and therefore reducing load. I would suggest that your power reduction is actually a bit less as from the figures given the droop is 7/5 % which is a bit high. If the frequency excursion is short-lived, the meter may not be responding fast enough to indicate the full extent of the transient.
Bruce.
This question has been covered many times before in many ways on control.com. Use the 'Search' feature to search for Pre-Select Load or Preselect Load or Droop Speed Control for more detailed descriptions (you'll find a lot of references).
You have not provided us with enough information to answer your question. We don't know how your unit is being operated, whether there is some kind of external load control, if it's in "straight" Droop Speed Control or Pre-Selected Load Control or at Base Load or what.
There are just to many situations to try to cover them all here without causing confusion.
I will say this much: It is the desired response of generators operating in parallel with each other to reduce load when the grid frequency increases above rated. It is the intent of Droop Speed Control to have machines operating at partial load to respond to changes in grid frequency to try to maintain rated frequency, automatically and without operator intervention. That goes for decreases below rated frequency as well as increases above rated frequency. That's the "side" benefit of Droop Speed Control, if you will. Which has been discussed ad nauseum and ad infinitem here on control.com.
But, we just don't have enough information to respond to this question. And, you should research the topics above and ask questions along with providing more information about the precise operating conditions of the unit when the suspect condition occurs (Base Load, Part Load, Pre-selected Load Control enabled or disabled: External Load Control enabled or disabled; any on-site or remote load control schemes in operation; etc.).
You have not provided us with enough information to answer your question. We don't know how your unit is being operated, whether there is some kind of external load control, if it's in "straight" Droop Speed Control or Pre-Selected Load Control or at Base Load or what.
There are just to many situations to try to cover them all here without causing confusion.
I will say this much: It is the desired response of generators operating in parallel with each other to reduce load when the grid frequency increases above rated. It is the intent of Droop Speed Control to have machines operating at partial load to respond to changes in grid frequency to try to maintain rated frequency, automatically and without operator intervention. That goes for decreases below rated frequency as well as increases above rated frequency. That's the "side" benefit of Droop Speed Control, if you will. Which has been discussed ad nauseum and ad infinitem here on control.com.
But, we just don't have enough information to respond to this question. And, you should research the topics above and ask questions along with providing more information about the precise operating conditions of the unit when the suspect condition occurs (Base Load, Part Load, Pre-selected Load Control enabled or disabled: External Load Control enabled or disabled; any on-site or remote load control schemes in operation; etc.).
S
surya
thank you for your reply, but i have still one doubt that when the speed of turbine increases the governor tries to increase the fuel flow. but in your answer you said that governor will reduce the speed and load also increases
I'm in total agreement with CSA... Response of your generator is very dependant on gen/system parameters, such as:
o Generator characteristics.
o Load characteristic.
o Local power requirement.
o Connection to grid: GSU Xfmr? OVH tranmission line?
Please abide by CSA's comment to provide detail!
Phil Corso
o Generator characteristics.
o Load characteristic.
o Local power requirement.
o Connection to grid: GSU Xfmr? OVH tranmission line?
Please abide by CSA's comment to provide detail!
Phil Corso
J
jojo
I would look at the problem from a different angle.
I would say that your GT frequency (speed) increased because your system lost connected load, somewhere to the tune of 20MW. I am assuming that your GT was running in droop control, to have unloaded to 100MW when the frequency rose to 50.5Hz.
Keep in mind that the generator follows the load and not vice-versa.
I would say that your GT frequency (speed) increased because your system lost connected load, somewhere to the tune of 20MW. I am assuming that your GT was running in droop control, to have unloaded to 100MW when the frequency rose to 50.5Hz.
Keep in mind that the generator follows the load and not vice-versa.
