Our Steam turbine tripped on speed controller trip alarm when we synchronized it on auto in slow synchronization mode. If all machine tripped on slow synchronization mode then why on auto it's breaker closed and then tripped? What will be the cause of it ? Which solution you will suggest us.
Machine tripped
- Thread starter Eagle
- Start date
When this issue appeared?
Any outage /inspection done these last days ?
We cannot provide better support as we dont have the application code/control system software ...
So if you ok to share programm of this STG ...we can be a better support
Any outage /inspection done these last days ?
We cannot provide better support as we dont have the application code/control system software ...
So if you ok to share programm of this STG ...we can be a better support
Dear,
SOOO little information, and SOOO many questions.
Who manufactured the steam turbine?
What control system is used on the steam turbine?
What alarms were present at the time of synchronization? (In other words, what were the active alarms prior to and during the synchronization?)
What synchronizer relay/system is used for this steam turbine-generator?
Why did you choose "slow synchronization" which implies there is another synchronization method (normal or fast???)?
What was the grid frequency during the synchronization attempt? Was it at rated, or below rated, or above rated, or unstable and erratic?
SPECIFICALLY, what was the alarm message which was indicated when the unit tripped after synchronization?
What governor mode was the turbine control system operating in when the unit was being synchronized: Droop Speed Control or Isochronous Speed Control?
Were you synchronizing to a grid with other multiple other prime movers and generators, or were you synchronizing to one or a small number of prime movers and generators?
What was the power output of the machine when the generator was closed after synchronization? Was it stable, above zero, below zero, unstable?
What was the generator terminal voltage after synchronization? Stable, above normal, less than normal, unstable?
As ControlsGuy25 wrote, it would be very helpful if we could see the program running in the turbine control system. It would also be helpful if we understood the electrical system of the generator and the system being synchronized to. Finally, some steam turbine control systems have synchronization capability, and many others do not and so they employ synchronizers made by other manufacturers. I hope you understand there is very little we can recommend if we don't some of the very basics of the plant configuration and equipment. Yes, you are writing to a World Wide Web forum with experts (how they became experts and/or were certified as experts remains a mystery) and while it would be awesome and wonderful if one could just say what you said, "My turbine tripped slightly after synchronization; what do I do?" that's just simply NOT realistic. If you have a GE Mark* turbine control system there are things we could tell you to check or monitor on the next synchronization attempt, but we would still be making a few assumptions without really understanding the high-voltage electrical system at the plant. But you didn't tell us anything about the equipment and configuration, not even how long the machine was synchronized before it tripped after the generator breaker closed.
AND, knowing what the frequency of the system the unit was being synchronized to at the time of synchronization would also be very helpful--if only to eliminate an unstable system as part of, or the root cause of, the problem. If the turbine tripped because the frequency was very low after synchronization then it's very possible the speed controller tripped the machine, though it could also have been the machine's under-frequency relay. (Steam turbines really don't like running at less than rated speed (synchronous speed) while producing power.
Again, you haven't provided us with much to analyze or work with. You want help? We need information, and answering the above questions would be most helpful as a start. When a synchronous generator is synchronized to a grid/system with other prime movers and their generators the speed of the prime mover and generator is directly controlled by the frequency of the grid/system. It can't be any other way for AC (Alternating Current) power generation. If the grid/system frequency is low, the machine speed and generator frequency will also be low; if the grid frequency is high the machine speed and generator frequency will also be high. And, if the grid frequency is not stable and is erratic then the machine speed and generator frequency will be unstable and erratic when synchronized to the system/grid. Period. Full stop. No matter how much anyone wants it to be different (meaning they want "their" machine to be operating at a stable frequency when the system/grid it is synchronized to is unstable, and the power output is also unstable (because that's what happens when the grid frequency is unstable, too)) it just can't be. Different. If you want 50 Hz available from the electrical socket in the wall EVERY machine on the grid has to be at 50 Hz. One can't be at 50.1 Hz while several of the others are at 49.3 Hz and some others are at 50.6 Hz; AC power generation just doesn't work that way.
AND if you are trying to synchronize a machine to an unstable grid that's just an iffy proposition--meaning it might go "smoothly" and it might not; there are no guarantees.
And because we don't know any of that information, we just can't be of much help. There are a LOT of possibilities; these are just some of the more typical causes of problems. And, without knowing what turbine control system is being used on the machine, and what the synchronization scheme looks like, we are unable to help.
SOOO little information, and SOOO many questions.
Who manufactured the steam turbine?
What control system is used on the steam turbine?
What alarms were present at the time of synchronization? (In other words, what were the active alarms prior to and during the synchronization?)
What synchronizer relay/system is used for this steam turbine-generator?
Why did you choose "slow synchronization" which implies there is another synchronization method (normal or fast???)?
What was the grid frequency during the synchronization attempt? Was it at rated, or below rated, or above rated, or unstable and erratic?
SPECIFICALLY, what was the alarm message which was indicated when the unit tripped after synchronization?
What governor mode was the turbine control system operating in when the unit was being synchronized: Droop Speed Control or Isochronous Speed Control?
Were you synchronizing to a grid with other multiple other prime movers and generators, or were you synchronizing to one or a small number of prime movers and generators?
What was the power output of the machine when the generator was closed after synchronization? Was it stable, above zero, below zero, unstable?
What was the generator terminal voltage after synchronization? Stable, above normal, less than normal, unstable?
As ControlsGuy25 wrote, it would be very helpful if we could see the program running in the turbine control system. It would also be helpful if we understood the electrical system of the generator and the system being synchronized to. Finally, some steam turbine control systems have synchronization capability, and many others do not and so they employ synchronizers made by other manufacturers. I hope you understand there is very little we can recommend if we don't some of the very basics of the plant configuration and equipment. Yes, you are writing to a World Wide Web forum with experts (how they became experts and/or were certified as experts remains a mystery) and while it would be awesome and wonderful if one could just say what you said, "My turbine tripped slightly after synchronization; what do I do?" that's just simply NOT realistic. If you have a GE Mark* turbine control system there are things we could tell you to check or monitor on the next synchronization attempt, but we would still be making a few assumptions without really understanding the high-voltage electrical system at the plant. But you didn't tell us anything about the equipment and configuration, not even how long the machine was synchronized before it tripped after the generator breaker closed.
AND, knowing what the frequency of the system the unit was being synchronized to at the time of synchronization would also be very helpful--if only to eliminate an unstable system as part of, or the root cause of, the problem. If the turbine tripped because the frequency was very low after synchronization then it's very possible the speed controller tripped the machine, though it could also have been the machine's under-frequency relay. (Steam turbines really don't like running at less than rated speed (synchronous speed) while producing power.
Again, you haven't provided us with much to analyze or work with. You want help? We need information, and answering the above questions would be most helpful as a start. When a synchronous generator is synchronized to a grid/system with other prime movers and their generators the speed of the prime mover and generator is directly controlled by the frequency of the grid/system. It can't be any other way for AC (Alternating Current) power generation. If the grid/system frequency is low, the machine speed and generator frequency will also be low; if the grid frequency is high the machine speed and generator frequency will also be high. And, if the grid frequency is not stable and is erratic then the machine speed and generator frequency will be unstable and erratic when synchronized to the system/grid. Period. Full stop. No matter how much anyone wants it to be different (meaning they want "their" machine to be operating at a stable frequency when the system/grid it is synchronized to is unstable, and the power output is also unstable (because that's what happens when the grid frequency is unstable, too)) it just can't be. Different. If you want 50 Hz available from the electrical socket in the wall EVERY machine on the grid has to be at 50 Hz. One can't be at 50.1 Hz while several of the others are at 49.3 Hz and some others are at 50.6 Hz; AC power generation just doesn't work that way.
AND if you are trying to synchronize a machine to an unstable grid that's just an iffy proposition--meaning it might go "smoothly" and it might not; there are no guarantees.
And because we don't know any of that information, we just can't be of much help. There are a LOT of possibilities; these are just some of the more typical causes of problems. And, without knowing what turbine control system is being used on the machine, and what the synchronization scheme looks like, we are unable to help.
Dear,
There are many questions at the beginning of my initial response.
And, if this has been an ongoing issue for this machine (are there other machines with similar issues???) it would seem that there is either a problem with the configuration of "slow synchronization" (again--a term I am not familiar with, and it would help if you would explain what it is and how you think it's supposed to work), a problem with relay settings, or improper operation.
Steam turbines do not like reverse power. Reverse power occurs when the steam flow through the turbine is not sufficient to keep the steam turbine spinning at the speed which is proportional to the frequency of the grid/system the machine is synchronized to. So, electrical power flows into the generator from the grid/system turning the generator into a motor which keeps the generator and turbine spinning at the speed which is proportional to the frequency of the grid/system the machine is synchronized to. For a steam turbine this can cause the turbine blades to experience forces opposite to those they normally experience when steam flow is normal, and can also lead to heating of the steam turbine blades as they rotate faster than the steam that's flowing through the machine. This is NOT good for a steam turbine and many steam turbines--especially large steam turbines (more than 100 MW)--will trip the machine if the electrical power output of the machine/generator is only at 1- or 2- or 3 MW to protect the turbine from damage. (Reverse power does not damage the generator (most synchronous generators that is), but it is definitely not good for steam turbines.)
What is the steam turbine rating (kW or MW)?
Which direction does the synchronoscope rotate when "slow synchronization" is selected? Clockwise or anti-clockwise?
If it's rotating in the anti-clockwise direction during "slow synchronization" (which would be atypical for most steam turbines) at the instant the generator breaker closes the machine will immediately "draw" reverse power from the grid/system it is synchronized to because there is not sufficient steam flow to make the generator run at the speed which is proportional to the frequency of the grid/system the machine is synchronized to. If this is what's happening the steam turbine governor (control system) should be immediately increasing the steam flow into the turbine to quickly get into positive power (positive kW/MW). It could be that the steam turbine control system--or even some other PMS (Power Management System) which is monitoring multiple machines could be tripping the machine.
Do I need to number the questions for you to respond to? A sentence that ends with a question mark--?--is almost always a question, which needs an answer.
Start with the easy questions: Who makes the steam turbine and generator?
What is the rating of the turbine generator (kW, or MW)?
What control system is used on the steam turbine (you call it a speed controller; it's generically called a governor or speed governor; often it's called a turbine control system (whether it's a purpose-built turbine control system, or a PLC or a generic governor)?
What controls the automatic synchronization sequence/process (the speed matching, the voltage matching, the closing of the generator breaker at the correct instant in time)?
To the best of your ability please describe why there is a "slow synchronization" mode, and what does it look like (which direction does the synchroscope rotate during "slow synchronization, etc.)? Why is necessary to use "slow synchronization" as opposed to "normal" synchronization?
How well is the frequency of the grid/system the machine synchronizes to regulated? Is the frequency stable? Is it usually higher or lower than system rating? Is the grid frequency erratic sometimes when trying to synchronize? Is it erratic when the machine is synchronized?
Answering these questions will be helpful.
I'm sure your first language isn't English, and that's okay. Do your best.
But answer the questions.
There are many questions at the beginning of my initial response.
And, if this has been an ongoing issue for this machine (are there other machines with similar issues???) it would seem that there is either a problem with the configuration of "slow synchronization" (again--a term I am not familiar with, and it would help if you would explain what it is and how you think it's supposed to work), a problem with relay settings, or improper operation.
Steam turbines do not like reverse power. Reverse power occurs when the steam flow through the turbine is not sufficient to keep the steam turbine spinning at the speed which is proportional to the frequency of the grid/system the machine is synchronized to. So, electrical power flows into the generator from the grid/system turning the generator into a motor which keeps the generator and turbine spinning at the speed which is proportional to the frequency of the grid/system the machine is synchronized to. For a steam turbine this can cause the turbine blades to experience forces opposite to those they normally experience when steam flow is normal, and can also lead to heating of the steam turbine blades as they rotate faster than the steam that's flowing through the machine. This is NOT good for a steam turbine and many steam turbines--especially large steam turbines (more than 100 MW)--will trip the machine if the electrical power output of the machine/generator is only at 1- or 2- or 3 MW to protect the turbine from damage. (Reverse power does not damage the generator (most synchronous generators that is), but it is definitely not good for steam turbines.)
What is the steam turbine rating (kW or MW)?
Which direction does the synchronoscope rotate when "slow synchronization" is selected? Clockwise or anti-clockwise?
If it's rotating in the anti-clockwise direction during "slow synchronization" (which would be atypical for most steam turbines) at the instant the generator breaker closes the machine will immediately "draw" reverse power from the grid/system it is synchronized to because there is not sufficient steam flow to make the generator run at the speed which is proportional to the frequency of the grid/system the machine is synchronized to. If this is what's happening the steam turbine governor (control system) should be immediately increasing the steam flow into the turbine to quickly get into positive power (positive kW/MW). It could be that the steam turbine control system--or even some other PMS (Power Management System) which is monitoring multiple machines could be tripping the machine.
Do I need to number the questions for you to respond to? A sentence that ends with a question mark--?--is almost always a question, which needs an answer.
Start with the easy questions: Who makes the steam turbine and generator?
What is the rating of the turbine generator (kW, or MW)?
What control system is used on the steam turbine (you call it a speed controller; it's generically called a governor or speed governor; often it's called a turbine control system (whether it's a purpose-built turbine control system, or a PLC or a generic governor)?
What controls the automatic synchronization sequence/process (the speed matching, the voltage matching, the closing of the generator breaker at the correct instant in time)?
To the best of your ability please describe why there is a "slow synchronization" mode, and what does it look like (which direction does the synchroscope rotate during "slow synchronization, etc.)? Why is necessary to use "slow synchronization" as opposed to "normal" synchronization?
How well is the frequency of the grid/system the machine synchronizes to regulated? Is the frequency stable? Is it usually higher or lower than system rating? Is the grid frequency erratic sometimes when trying to synchronize? Is it erratic when the machine is synchronized?
Answering these questions will be helpful.
I'm sure your first language isn't English, and that's okay. Do your best.
But answer the questions.
