Speed control active
- Thread starter Dean
- Start date
Scroll to continue with content
Dude,
You gotta provide more information than that.
Who is the manufacturer of the machine?
What turbine control system is used to control and protect the turbine and auxiliaries?
What is the 100% rated speed of the turbine?
Is there a reduction gear between the turbine and the generator? If so, what is the nameplate rating of the reduction gear (RPM IN to RPM OUT)?
Is the machine synchronized to a grid or power distribution system with one or more generators and their prime movers?
What is the grid/power system frequency doing when this event occurs? Is it stable? Or is it oscillating? Or does it rise to one frequency and remain their for a while?
What happens to the load when this event occurs? Does it increase or decrease or just stay the same?
3698.5 RPM/ 3600 RPM = 1.0273 x 100 = 102.73%
If the machine is rated at 3600 RPM (a common speed for a machine producing 60 Hz), 3698.5 RPM is 102.73% of rated speed. Of course we are presuming the machine is a 60 Hz machine--because we don't know that because you didn't tell us much of anything about the machine or the conditions during the event.
Most machines would trip the generator breaker if the frequency (speed) went up to 102.73% (which would be 61.638 Hz).
You want help? We need MORE information--specifically the answers to all the questions above.
AND, if the turbine control system is a GE Mark* control system what were them alarms (Process Alarms & Diagnostic Alarms) at the time of the events? Because the alarms could help us understand a lot about what was going on at the times of the events.
Give us the answers and we can probably help you.
You gotta provide more information than that.
Who is the manufacturer of the machine?
What turbine control system is used to control and protect the turbine and auxiliaries?
What is the 100% rated speed of the turbine?
Is there a reduction gear between the turbine and the generator? If so, what is the nameplate rating of the reduction gear (RPM IN to RPM OUT)?
Is the machine synchronized to a grid or power distribution system with one or more generators and their prime movers?
What is the grid/power system frequency doing when this event occurs? Is it stable? Or is it oscillating? Or does it rise to one frequency and remain their for a while?
What happens to the load when this event occurs? Does it increase or decrease or just stay the same?
3698.5 RPM/ 3600 RPM = 1.0273 x 100 = 102.73%
If the machine is rated at 3600 RPM (a common speed for a machine producing 60 Hz), 3698.5 RPM is 102.73% of rated speed. Of course we are presuming the machine is a 60 Hz machine--because we don't know that because you didn't tell us much of anything about the machine or the conditions during the event.
Most machines would trip the generator breaker if the frequency (speed) went up to 102.73% (which would be 61.638 Hz).
You want help? We need MORE information--specifically the answers to all the questions above.
AND, if the turbine control system is a GE Mark* control system what were them alarms (Process Alarms & Diagnostic Alarms) at the time of the events? Because the alarms could help us understand a lot about what was going on at the times of the events.
Give us the answers and we can probably help you.
Dude,
You gotta provide more information than that.
Who is the manufacturer of the machine?
Mitsubishi Gas Turbine
What turbine control system is used to control and protect the turbine and auxiliaries?
Netmation
What is the 100% rated speed of the turbine?
3600
Is there a reduction gear between the turbine and the generator? If so, what is the nameplate rating of the reduction gear (RPM IN to RPM OUT)?
No reduction gear
Is the machine synchronized to a grid or power distribution system with one or more generators and their prime movers?
Connected to Grid
What is the grid/power system frequency doing when this event occurs? Is it stable? Or is it oscillating? Or does it rise to one frequency and remain there for a while?
Varies this speed same as grid
What happens to the load when this event occurs? Does it increase or decrease or just stay the same?
GT can’t reach base load and remains on speed control
3698.5 RPM/ 3600 RPM = 1.0273 x 100 = 102.73%
I mistyped, it’s 3598.5 rpm
If the machine is rated at 3600 RPM (a common speed for a machine producing 60 Hz), 3698.5 RPM is 102.73% of rated speed. Of course we are presuming the machine is a 60 Hz machine--because we don't know that because you didn't tell us much of anything about the machine or the conditions during the event.
Most machines would trip the generator breaker if the frequency (speed) went up to 102.73% (which would be 61.638 Hz).
You want help? We need MORE information--specifically the answers to all the questions above.
AND, if the turbine control system is a GE Mark* control system what were them alarms (Process Alarms & Diagnostic Alarms) at the time of the events? Because the alarms could help us understand a lot about what was going on at the times of the events.
Give us the answers and we can probably help you.
You wrote, “Varies this speed same as grid,” in response to what happens grid frequency during this event. That implies the grid frequency is not being maintained very well.
You haven’t said what the load (MW) was at the time of this event, only that it can’t reach Base Load and remains on speed control. IS THAT DROOP SPEED CONTROL OR ISOCHRONOUS SPEED CONTROL?
WHAT ARE THE ALARMS ((ALL of them) AT THE TIME OF THIS EVENT?
IS THE MACHINE BEING LOADED (IS THE LOAD BEING INCREASED (EITHER AUTOMATICALLY OR MANUALLY) WHEN THE EVENT OCCURS?
IS THE MACHINE UNDER LOCAL OR REMOTE CONTROL AT THE TIME OF THE EVENT?
HAS AN OPERATOR TRIED TO INCREASE (OR DECREASE) LOAD AFTER THE MACHINE STOPS INCREASING LOAD WHEN THIS EVENT OCCURS? IF SO, HOW DOES THE OPERATOR ATTEMPT TO INCREASE LOAD AND WHAT HAPPENS WHEN THE OPERATOR ATTEMPTS TO INCREASE LOAD? IS THERE ANY ALARM(S) WHEN THE OPERATOR ATTEMPTS TO INCREASE LOAD AND IF SO, WHAT ARE THE ALARMS?
Please remember: We aren’t there to see what you are seeing so you have to tell us what is happening prior to and during this event—and what is the machine control system doing (what alarms is it annunciating)?
I’m not familiar with Mitsubishi heavy duty gas turbine control philosophy but it seems as if the machine is being loaded automatically and something is happening to cancel the automatic loading and the machine stops increasing load. That’s all I can say based on the information you are providing. You seem to be trying to say the machine is being loaded automatically (for example, Base Load was selected and the Netmation control system was ramping machine
load up and something happened to cancel the automatic load increase—but we don’t know what happened or why. You haven’t told us what happens after the load stops increasing. How is load eventually increased or decreased?
Is it possible that the grid frequency decrease cancels the automatic load increase until an operator takes some action? 1.5 RPM is a very small amount of RPM change (it’s only a 0.04% speed change, and a 0.04% frequency change (to 59.975 Hz)). It’s not unusual for grid frequency in some places to fluctuate by that amount without any significant harm to the grid.
So, help us to understand what is happening at the time of the event; what alarms are being annunciated during the event; what does the operator do to get the machine to load/unload after the event? Is the machine even being loaded prior to the event? A turbine control system should be alerting the operator to the condition that is canceling the automatic loading or preventing automatic or manual loading by some alarm so the operator can take appropriate action. You haven’t told us what the load is before the event, and if the load was being increased before the event, and how is load being changed after the event? A 1.5 RPM change is very little.
You haven’t said what the load (MW) was at the time of this event, only that it can’t reach Base Load and remains on speed control. IS THAT DROOP SPEED CONTROL OR ISOCHRONOUS SPEED CONTROL?
WHAT ARE THE ALARMS ((ALL of them) AT THE TIME OF THIS EVENT?
IS THE MACHINE BEING LOADED (IS THE LOAD BEING INCREASED (EITHER AUTOMATICALLY OR MANUALLY) WHEN THE EVENT OCCURS?
IS THE MACHINE UNDER LOCAL OR REMOTE CONTROL AT THE TIME OF THE EVENT?
HAS AN OPERATOR TRIED TO INCREASE (OR DECREASE) LOAD AFTER THE MACHINE STOPS INCREASING LOAD WHEN THIS EVENT OCCURS? IF SO, HOW DOES THE OPERATOR ATTEMPT TO INCREASE LOAD AND WHAT HAPPENS WHEN THE OPERATOR ATTEMPTS TO INCREASE LOAD? IS THERE ANY ALARM(S) WHEN THE OPERATOR ATTEMPTS TO INCREASE LOAD AND IF SO, WHAT ARE THE ALARMS?
Please remember: We aren’t there to see what you are seeing so you have to tell us what is happening prior to and during this event—and what is the machine control system doing (what alarms is it annunciating)?
I’m not familiar with Mitsubishi heavy duty gas turbine control philosophy but it seems as if the machine is being loaded automatically and something is happening to cancel the automatic loading and the machine stops increasing load. That’s all I can say based on the information you are providing. You seem to be trying to say the machine is being loaded automatically (for example, Base Load was selected and the Netmation control system was ramping machine
load up and something happened to cancel the automatic load increase—but we don’t know what happened or why. You haven’t told us what happens after the load stops increasing. How is load eventually increased or decreased?
Is it possible that the grid frequency decrease cancels the automatic load increase until an operator takes some action? 1.5 RPM is a very small amount of RPM change (it’s only a 0.04% speed change, and a 0.04% frequency change (to 59.975 Hz)). It’s not unusual for grid frequency in some places to fluctuate by that amount without any significant harm to the grid.
So, help us to understand what is happening at the time of the event; what alarms are being annunciated during the event; what does the operator do to get the machine to load/unload after the event? Is the machine even being loaded prior to the event? A turbine control system should be alerting the operator to the condition that is canceling the automatic loading or preventing automatic or manual loading by some alarm so the operator can take appropriate action. You haven’t told us what the load is before the event, and if the load was being increased before the event, and how is load being changed after the event? A 1.5 RPM change is very little.
With GE machines, the Mark* turbine control system has a load selection on the Main Display, one can choose BASE LOAD, PEAK LOAD (if the option is available for the machine) and PRE-SELECT Load Control. MANY sites and operators use Pre-Selected Load Control to increase and decrease load on the machine by changing a Pre-Selected Load Control Reference, and when they want to go to Base Load they just put in a Pre-Selected Load Reference that is higher than they think the machine can make instead of just clicking on BASE LOAD. While this works, it can cause other problems for loading and unloading.
I don't know how the Netmation transitions from Droop Speed Control to exhaust temperature control but if your site is doing something similar to load the machine and inputting a load control reference that is very close to the actual Base Load rating of the machine at the time then when the grid frequency decreases it could cause the machine to go back to Droop Speed Control. The GE Mark* turbine control system, when BASE LOAD is selected and active actually raises the turbine speed reference to a value that is higher than the exhaust temperature reference and maintains a constant differential so that the control won't bounce between Droop Speed Control and exhaust temperature control. Essentially the machine is operating at Base Load, but the status messages on the displays bounce between Part Load (which is Droop Speed Control) and Temp Control (exhaust temperature control), which confuses a lot of people--but that's because they haven't really selected BASE LOAD and the Pre-Selected Load Control reference for that time of day/year results in this bouncing between speed control (Part Load) and exhaust temperature control (Base Load). I suspect that this may be what you are trying to describe, but without knowing how the machine is being operated at your site (how it is loaded and unloaded) and how the Netmation transitions between Droop Speed Control and exhaust temperature control it's very difficult to say exactly what is happening.
If you could describe how an operator loads and unloads the machine (is it done by changing a load control reference, say, the machine is operating at 50 MW and the operator inputs a load reference of 60 MW and the machine automatically ramps up to 60 MW, and when unloading the machine from 90 MW the operator puts in a load control reference of 70 MW and the machine automatically ramps down to 70 MW) that would be very helpful to this discussion.
If the operator puts in a load control reference that is nearly equal to the Base Load rating of the turbine to load it to Base Load, instead of selecting BASE LOAD (if that's an option on the Netmation), say, the machine is rated at 150 MW and the operator puts in 150 MW on an order to go to Base Load, and the machine loads until it reaches 150 MW--which is right on the transition from Droop Speed Control to exhaust temperature control (Base Load), and then the grid frequency decreases a little and the machine gets shifted back to Droop Speed Control something like this could be the reason for what you are trying to describe.
That's why it's important for you to tell us how the machine is typically operated. It may be that there are pre-programmed load references and the operator just clicks on them to change load, and that the highest load reference is at or just slightly above or below the Base Load capability of the machine on a particular day. It would be EXTREMELY helpful for you to tell us what the Base Load nameplate rating of the machine is AND what load the machine is producing at the time of this event. As well as how the machine is typically loaded and unloaded.
One last question: When did this problem start? Has is been ongoing since commissioning, or is it just something that started in the last week or so? If it's something that started in the last week (or month), what happened to the machine/control system just before this started occurring? Was there a maintenance outage on the machine? An off-line water wash? Some change to the Netmation (upgrade; software modification of some sort)? An unexpected trip from load? Anything you can tell us will be of help--because we are not there alongside you and we don't know what you know. Often, as has been said MANY times on Control.com, troubleshooting is a process of elimination and right now we don't have enough information to know what it might OR might not be. Help us to help you.
I don't know how the Netmation transitions from Droop Speed Control to exhaust temperature control but if your site is doing something similar to load the machine and inputting a load control reference that is very close to the actual Base Load rating of the machine at the time then when the grid frequency decreases it could cause the machine to go back to Droop Speed Control. The GE Mark* turbine control system, when BASE LOAD is selected and active actually raises the turbine speed reference to a value that is higher than the exhaust temperature reference and maintains a constant differential so that the control won't bounce between Droop Speed Control and exhaust temperature control. Essentially the machine is operating at Base Load, but the status messages on the displays bounce between Part Load (which is Droop Speed Control) and Temp Control (exhaust temperature control), which confuses a lot of people--but that's because they haven't really selected BASE LOAD and the Pre-Selected Load Control reference for that time of day/year results in this bouncing between speed control (Part Load) and exhaust temperature control (Base Load). I suspect that this may be what you are trying to describe, but without knowing how the machine is being operated at your site (how it is loaded and unloaded) and how the Netmation transitions between Droop Speed Control and exhaust temperature control it's very difficult to say exactly what is happening.
If you could describe how an operator loads and unloads the machine (is it done by changing a load control reference, say, the machine is operating at 50 MW and the operator inputs a load reference of 60 MW and the machine automatically ramps up to 60 MW, and when unloading the machine from 90 MW the operator puts in a load control reference of 70 MW and the machine automatically ramps down to 70 MW) that would be very helpful to this discussion.
If the operator puts in a load control reference that is nearly equal to the Base Load rating of the turbine to load it to Base Load, instead of selecting BASE LOAD (if that's an option on the Netmation), say, the machine is rated at 150 MW and the operator puts in 150 MW on an order to go to Base Load, and the machine loads until it reaches 150 MW--which is right on the transition from Droop Speed Control to exhaust temperature control (Base Load), and then the grid frequency decreases a little and the machine gets shifted back to Droop Speed Control something like this could be the reason for what you are trying to describe.
That's why it's important for you to tell us how the machine is typically operated. It may be that there are pre-programmed load references and the operator just clicks on them to change load, and that the highest load reference is at or just slightly above or below the Base Load capability of the machine on a particular day. It would be EXTREMELY helpful for you to tell us what the Base Load nameplate rating of the machine is AND what load the machine is producing at the time of this event. As well as how the machine is typically loaded and unloaded.
One last question: When did this problem start? Has is been ongoing since commissioning, or is it just something that started in the last week or so? If it's something that started in the last week (or month), what happened to the machine/control system just before this started occurring? Was there a maintenance outage on the machine? An off-line water wash? Some change to the Netmation (upgrade; software modification of some sort)? An unexpected trip from load? Anything you can tell us will be of help--because we are not there alongside you and we don't know what you know. Often, as has been said MANY times on Control.com, troubleshooting is a process of elimination and right now we don't have enough information to know what it might OR might not be. Help us to help you.
Yes it is mainly operated on AGC(remote)With GE machines, the Mark* turbine control system has a load selection on the Main Display, one can choose BASE LOAD, PEAK LOAD (if the option is available for the machine) and PRE-SELECT Load Control. MANY sites and operators use Pre-Selected Load Control to increase and decrease load on the machine by changing a Pre-Selected Load Control Reference, and when they want to go to Base Load they just put in a Pre-Selected Load Reference that is higher than they think the machine can make instead of just clicking on BASE LOAD. While this works, it can cause other problems for loading and unloading.
I don't know how the Netmation transitions from Droop Speed Control to exhaust temperature control but if your site is doing something similar to load the machine and inputting a load control reference that is very close to the actual Base Load rating of the machine at the time then when the grid frequency decreases it could cause the machine to go back to Droop Speed Control. The GE Mark* turbine control system, when BASE LOAD is selected and active actually raises the turbine speed reference to a value that is higher than the exhaust temperature reference and maintains a constant differential so that the control won't bounce between Droop Speed Control and exhaust temperature control. Essentially the machine is operating at Base Load, but the status messages on the displays bounce between Part Load (which is Droop Speed Control) and Temp Control (exhaust temperature control), which confuses a lot of people--but that's because they haven't really selected BASE LOAD and the Pre-Selected Load Control reference for that time of day/year results in this bouncing between speed control (Part Load) and exhaust temperature control (Base Load). I suspect that this may be what you are trying to describe, but without knowing how the machine is being operated at your site (how it is loaded and unloaded) and how the Netmation transitions between Droop Speed Control and exhaust temperature control it's very difficult to say exactly what is happening.
If you could describe how an operator loads and unloads the machine (is it done by changing a load control reference, say, the machine is operating at 50 MW and the operator inputs a load reference of 60 MW and the machine automatically ramps up to 60 MW, and when unloading the machine from 90 MW the operator puts in a load control reference of 70 MW and the machine automatically ramps down to 70 MW) that would be very helpful to this discussion.
If the operator puts in a load control reference that is nearly equal to the Base Load rating of the turbine to load it to Base Load, instead of selecting BASE LOAD (if that's an option on the Netmation), say, the machine is rated at 150 MW and the operator puts in 150 MW on an order to go to Base Load, and the machine loads until it reaches 150 MW--which is right on the transition from Droop Speed Control to exhaust temperature control (Base Load), and then the grid frequency decreases a little and the machine gets shifted back to Droop Speed Control something like this could be the reason for what you are trying to describe.
That's why it's important for you to tell us how the machine is typically operated. It may be that there are pre-programmed load references and the operator just clicks on them to change load, and that the highest load reference is at or just slightly above or below the Base Load capability of the machine on a particular day. It would be EXTREMELY helpful for you to tell us what the Base Load nameplate rating of the machine is AND what load the machine is producing at the time of this event. As well as how the machine is typically loaded and unloaded.
One last question: When did this problem start? Has is been ongoing since commissioning, or is it just something that started in the last week or so? If it's something that started in the last week (or month), what happened to the machine/control system just before this started occurring? Was there a maintenance outage on the machine? An off-line water wash? Some change to the Netmation (upgrade; software modification of some sort)? An unexpected trip from load? Anything you can tell us will be of help--because we are not there alongside you and we don't know what you know. Often, as has been said MANY times on Control.com, troubleshooting is a process of elimination and right now we don't have enough information to know what it might OR might not be. Help us to help you.
Operator does change the load as needed and set the MW set point
Rated MW is nearly 175 but have to double check , sorry as didn’t get chance to look to see name plate information
Thank you for everyone’s help
I would provide more details asap
Sorry forgot to mention what I knew is that yes it happens whether on local or remote mode and when we say Preselect , something we call here operator load Interestingly have been seeing this at more than 150 MW or higher IGV does not go full open as it is a function of MW and due to speed control output lower than temp control we swinging between load and speed control ( minimum output of the controllers)Yes it is mainly operated on AGC(remote)
Operator does change the load as needed and set the MW set point
Rated MW is nearly 175 but have to double check , sorry as didn’t get chance to look to see name plate information
Thank you for everyone’s help
I would provide more details asap
You need a Netmation person familiar with Mitsubishi heavy duty gas turbine control systems and philosophy. Sounds like there is some kind of minimum select function (as there is with GE Mark* heavy duty gas turbine control systems) and for some reason the two functions are unusually similar and close to each other.
Sorry; that's all I can add to this.
Sorry; that's all I can add to this.
You're welcome. You need someone on site who can see what you see and experience what you are experiencing. If you had provided the list of alarms prior to and during the event we MIGHT have been able to help you. I know--many alarm messages are cryptic, but not to everyone.
Best of luck! It would be really helpful if you could write back to let us know how this problem is resolved. REALLY helpful.
Best of luck! It would be really helpful if you could write back to let us know how this problem is resolved. REALLY helpful.
