MIKE-VI/ CSA,
It has really been a fruitful thread and I've learned so much. One thing that I have noticed at my site and which constantly bugs me is the operating modes in which both Gas Turbines are operated. As already stated, we are operating in island mode where one GT operates in Iso mode and other on Droop.
For Iso machine, the load control on Mark-VI is kept on manual and AFR is ON for Governer Control. Operator continuously monitors IGVs position to ensure that there is sufficient margin in them (around 15 deg below max) to cater for any sudden load change. If not, he/she sheds some load to create that margin. This part is understandable.
Now comes the part that bugs me. For the droop machine, naturally the AFR is OFF <b>but we also keep the load control on MANUAL</b>. The operator continuously presses the <i>raise/lower</i> pushbuttons on HMI to increase/decrease the load. Each press results in around 0.1MW change. (See attached snapshot of HMI for better clarity). Secondly, a 10 deg margin is also kept in Droop machine's IGVs and operator runs to lower the load when IGVs opening increase beyond 70 deg (Max 82 deg). I personally think that this practice is complete nonsense. The load control of Droop machine should be kept on AUTO and machine should be kept on base load i.e on max IGVs. The base load concept is also very misunderstood at our site with operators treating a predetermined value as base load regardless of other factors.
Link to HMI Snapshot:
https://drive.google.com/open?id=1zmNwbqh-UgIRz4dDAsuvW4qKO5FFefEF
What do you guys think? Shouldn't the droop machine be operated on AUTO and on base load? If the load control is on MANUAL and there is sufficient margin in IGVs, droop machine will always accept an instantaneous load in case of sudden load increase like that in our scenario when Tornado tripped.
P.S we've incorporated frequency based tripping in our LMS so I hope this event will never occur again!
It has really been a fruitful thread and I've learned so much. One thing that I have noticed at my site and which constantly bugs me is the operating modes in which both Gas Turbines are operated. As already stated, we are operating in island mode where one GT operates in Iso mode and other on Droop.
For Iso machine, the load control on Mark-VI is kept on manual and AFR is ON for Governer Control. Operator continuously monitors IGVs position to ensure that there is sufficient margin in them (around 15 deg below max) to cater for any sudden load change. If not, he/she sheds some load to create that margin. This part is understandable.
Now comes the part that bugs me. For the droop machine, naturally the AFR is OFF <b>but we also keep the load control on MANUAL</b>. The operator continuously presses the <i>raise/lower</i> pushbuttons on HMI to increase/decrease the load. Each press results in around 0.1MW change. (See attached snapshot of HMI for better clarity). Secondly, a 10 deg margin is also kept in Droop machine's IGVs and operator runs to lower the load when IGVs opening increase beyond 70 deg (Max 82 deg). I personally think that this practice is complete nonsense. The load control of Droop machine should be kept on AUTO and machine should be kept on base load i.e on max IGVs. The base load concept is also very misunderstood at our site with operators treating a predetermined value as base load regardless of other factors.
Link to HMI Snapshot:
https://drive.google.com/open?id=1zmNwbqh-UgIRz4dDAsuvW4qKO5FFefEF
What do you guys think? Shouldn't the droop machine be operated on AUTO and on base load? If the load control is on MANUAL and there is sufficient margin in IGVs, droop machine will always accept an instantaneous load in case of sudden load increase like that in our scenario when Tornado tripped.
P.S we've incorporated frequency based tripping in our LMS so I hope this event will never occur again!
