Automatic load throw by gas turbine & opening/closing of generator breaker on HMI

hello dear all !

We have a power plant with three Gas Turbines (Frame V GE model with Mark-VIe control) running in synchronism with national power grid. Based on the plant process load out plant runs either in power export or import mode. All the GTs are running in droop mode with LCM (load control module) set point fixed at around 18 MW (which can be changed based on plant load).
We have observed the following abnormal incidents :
1. Load on Gas Turbine-2 gradually reduced from 13 MW to 7 MW in and then increased back to set point (13MW),without giving any command by the operator.
2. On the second day, load on the same GT reduced to 2MW from 12.5 MW and the generator breaker indications on the HMI changed from CLOSED (red) to OPEN (green) and then again after 15-17 seconds become CLOSE from OPEN indication. GT continue to run normally though. We did not get any any alarms in the protection relay also. We have stopped the GT sensing some serious trouble.

Our instrument side says that Mark-VIe might get some breaker OPEN signal & that is why it is throwing load ( may be due to some loose contact) and before actually opening the breaker , the feedback become normal and the load on the GT again increases to normal, which is not convincing to us.

How can we explain the situation and why this is happening, our esteem forum may kindly throw some light on this. please help
 
hello dear all !

We have a power plant with three Gas Turbines (Frame V GE model with Mark-VIe control) running in synchronism with national power grid. Based on the plant process load out plant runs either in power export or import mode. All the GTs are running in droop mode with LCM (load control module) set point fixed at around 18 MW (which can be changed based on plant load).
We have observed the following abnormal incidents :
1. Load on Gas Turbine-2 gradually reduced from 13 MW to 7 MW in and then increased back to set point (13MW),without giving any command by the operator.
2. On the second day, load on the same GT reduced to 2MW from 12.5 MW and the generator breaker indications on the HMI changed from CLOSED (red) to OPEN (green) and then again after 15-17 seconds become CLOSE from OPEN indication. GT continue to run normally though. We did not get any any alarms in the protection relay also. We have stopped the GT sensing some serious trouble.

Our instrument side says that Mark-VIe might get some breaker OPEN signal & that is why it is throwing load ( may be due to some loose contact) and before actually opening the breaker , the feedback become normal and the load on the GT again increases to normal, which is not convincing to us.

How can we explain the situation and why this is happening, our esteem forum may kindly throw some light on this. please help
Dear @jagriti

Looks like your plant is encountering kind of Load swinging /shedding..or maybe sharing

Any work have been done on these units recently?

Can you confirm that LCM OR PMS (Power management system) is operating properly.

What about reactive power behaviour on these plant ?

Any process alarms annunciated on MarkVIe HMI? Any Alarms on GCPor GPP ( Generator Control/Protection Panel)

By the way what is :

AVR OEM
GPP OEM (IED protection relay)

Any SLD available ?

Thank you for replying to these questions so we can be a good assistance on this issue .

Regards
James
 
hello dear all !

We have a power plant with three Gas Turbines (Frame V GE model with Mark-VIe control) running in synchronism with national power grid. Based on the plant process load out plant runs either in power export or import mode. All the GTs are running in droop mode with LCM (load control module) set point fixed at around 18 MW (which can be changed based on plant load).
We have observed the following abnormal incidents :
1. Load on Gas Turbine-2 gradually reduced from 13 MW to 7 MW in and then increased back to set point (13MW),without giving any command by the operator.
2. On the second day, load on the same GT reduced to 2MW from 12.5 MW and the generator breaker indications on the HMI changed from CLOSED (red) to OPEN (green) and then again after 15-17 seconds become CLOSE from OPEN indication. GT continue to run normally though. We did not get any any alarms in the protection relay also. We have stopped the GT sensing some serious trouble.

Our instrument side says that Mark-VIe might get some breaker OPEN signal & that is why it is throwing load ( may be due to some loose contact) and before actually opening the breaker , the feedback become normal and the load on the GT again increases to normal, which is not convincing to us.

How can we explain the situation and why this is happening, our esteem forum may kindly throw some light on this. please help
Did u check behavior of gas valves during this?
Hydraulic pressure trend during incident?
 
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