- #1
girts
- 186
- 22
Before I begin I have to note that my last thread of this kind got heavily moderated and closed because the moderators did not like the specific way in which I was formulating my questions, so now I want to clarify and reaffirm some of what I have learned through questions without making any statements.
The following are all my questions and should not be taken as facts by anyone1) So from what I have read is it true that the grid frequency is primarily maintained (influenced) by keeping the rpm's of the synchronous generators attached to the grid constant (within the allowed margins) with the help of "flyball" centrifugal governors (older obsolete technology) or automatic electronics which control (increase or decrease) the torque supplied to the generator rotating axis based on the changes in grid frequency?
2) Since synchronous generator rotor rpm is directly linked to the output (stator) field frequency, does it then mean that in a situation where a large generator has abruptly went offline and the grid frequency has started to decrease (for example from 60hz to 59hz) that electronics would increase the torque supplied to the remaining generators in order to compensate for the decreased frequency?
3) I learned that synchronous generator rotor rpm is "locked" or in step with the stator field frequency (the reason why their called synchronous in the first place), so does that mean that in the mentioned example of a large generator going offline (or other large load coming online) the whole grid frequency for example drops by about 1hz, since all the generators are connected to the grid in parallel and their rotor rpm locked to the stator field, that means that now all the generators rotor rpm drops by some small amount which corresponds to the Hz of frequency lost?
Here is the part I would like to understand deeper, the speed (frequency) governors now "notice" this drop in frequency and apply more torque to each generators prime mover (assuming the prime mover has headroom or additional torque capacity ) what happens now? the generator rotor rpm are locked to grid frequency but grid frequency has dropped so has the rpm, the rotors now get supplied with more torque and by what process the grid frequency now gets back to normal can you please elaborate?
I would also like to post my own quick attempt to answer this. (I think that as the generators prime mover's torque gets increased the rotor B field is now "running" ahead of the stator field (which dropped to 59hz) by some angle, so if this is done on many (all?) generators at the same time it then has the capacity to alter the grid frequency quickly enough to set it back within the specified margins?)4) It must be that the speed aka frequency governor electronics and even the flyball governors in the old days must have been carefully synchronized ? Because in order to stabilize the grid frequency the response from each generator must have been quick but also the same so that all generators would work in unison correct?5) Automatic generator speed governor action to stabilize grid frequency is the first and quickest response to grid frequency fluctuation correct? But I read the next (longer) process is when the grid operator coordinates for some plants generators to output more "torque" to stabilize frequency in case of planned generator outages and repairs or other works?
thank you.
The following are all my questions and should not be taken as facts by anyone1) So from what I have read is it true that the grid frequency is primarily maintained (influenced) by keeping the rpm's of the synchronous generators attached to the grid constant (within the allowed margins) with the help of "flyball" centrifugal governors (older obsolete technology) or automatic electronics which control (increase or decrease) the torque supplied to the generator rotating axis based on the changes in grid frequency?
2) Since synchronous generator rotor rpm is directly linked to the output (stator) field frequency, does it then mean that in a situation where a large generator has abruptly went offline and the grid frequency has started to decrease (for example from 60hz to 59hz) that electronics would increase the torque supplied to the remaining generators in order to compensate for the decreased frequency?
3) I learned that synchronous generator rotor rpm is "locked" or in step with the stator field frequency (the reason why their called synchronous in the first place), so does that mean that in the mentioned example of a large generator going offline (or other large load coming online) the whole grid frequency for example drops by about 1hz, since all the generators are connected to the grid in parallel and their rotor rpm locked to the stator field, that means that now all the generators rotor rpm drops by some small amount which corresponds to the Hz of frequency lost?
Here is the part I would like to understand deeper, the speed (frequency) governors now "notice" this drop in frequency and apply more torque to each generators prime mover (assuming the prime mover has headroom or additional torque capacity ) what happens now? the generator rotor rpm are locked to grid frequency but grid frequency has dropped so has the rpm, the rotors now get supplied with more torque and by what process the grid frequency now gets back to normal can you please elaborate?
I would also like to post my own quick attempt to answer this. (I think that as the generators prime mover's torque gets increased the rotor B field is now "running" ahead of the stator field (which dropped to 59hz) by some angle, so if this is done on many (all?) generators at the same time it then has the capacity to alter the grid frequency quickly enough to set it back within the specified margins?)4) It must be that the speed aka frequency governor electronics and even the flyball governors in the old days must have been carefully synchronized ? Because in order to stabilize the grid frequency the response from each generator must have been quick but also the same so that all generators would work in unison correct?5) Automatic generator speed governor action to stabilize grid frequency is the first and quickest response to grid frequency fluctuation correct? But I read the next (longer) process is when the grid operator coordinates for some plants generators to output more "torque" to stabilize frequency in case of planned generator outages and repairs or other works?
thank you.