E
Power generation demand in my region has been sluggish in the recent years probably due to slow growth in big industrial ventures. Due to this, our power plant almost always be in partial load and often times asked to shutdown 1 unit during night time and started up again the next morning. Due to this, we have several problems with our system which I dont want to step into but one interesting problem is the MOOG servovalves.
As a general background, we have 2 units of Frame 6Bs, and have been running for 12 years or so. Control system is MarkVI TMR.
Recently during a routine startup after an overnight shutdown, the machine trips on GCV not following reference. Upon investigation, GCV could not be stroked past 92% and SRV could not be stroked past 89%. Looking at the servo currents, it seems like the VSVO could not drive the servos past these values. We replaced both servos and tried calibrating it again, same problem. We have encountered similar problem in the past 2 year where a GCV just straight up failed to operate and the only remedy is to replace the servovalve.
Funny thing is, during calibration, the servo can be driven up to 100% but immediately during manual stroke test, it fails to do so. We then move up to the controller debating the need to replace VSVO for T core which is the core that is not driving the servo(to my understanding, the servo valve can still be operated with 2, even 1 core) and we ended up restarting the whole controller.
Problem magically disappear and we returned to normal operation.
Any ideas what is happening here? Hiccups on MarkVI?
We are expecting a lot more problems to rise from these dispatch trends and just putting this out here for discussion.
Thank you!
As a general background, we have 2 units of Frame 6Bs, and have been running for 12 years or so. Control system is MarkVI TMR.
Recently during a routine startup after an overnight shutdown, the machine trips on GCV not following reference. Upon investigation, GCV could not be stroked past 92% and SRV could not be stroked past 89%. Looking at the servo currents, it seems like the VSVO could not drive the servos past these values. We replaced both servos and tried calibrating it again, same problem. We have encountered similar problem in the past 2 year where a GCV just straight up failed to operate and the only remedy is to replace the servovalve.
Funny thing is, during calibration, the servo can be driven up to 100% but immediately during manual stroke test, it fails to do so. We then move up to the controller debating the need to replace VSVO for T core which is the core that is not driving the servo(to my understanding, the servo valve can still be operated with 2, even 1 core) and we ended up restarting the whole controller.
Problem magically disappear and we returned to normal operation.
Any ideas what is happening here? Hiccups on MarkVI?
We are expecting a lot more problems to rise from these dispatch trends and just putting this out here for discussion.
Thank you!