AUTO LOAD SAHRING TROUBLE.

[nandantcr]

hi all,
recently I came across a problem with diesel generators when sharing load.
while in auto load sharing load fluctuates between the involved d/g's.
And the primary suspicion is that its Power management system module is not working well since the d/g's share load quite satisfactorily while paralleled in manual mode.
But doubt raised in my mind because while in auto load sharing the PMS is giving control command to raise and lower governor motor to regulate the load. But I suspects a small action on the governor motor is taking the d/g to other extreme and which causes the fluctuation.
My question is that if the governor motor response is too fast for the governor raise /governor lower signal is there is a chance for a difficult situation for the PMS to keep the load steady??? Or there is some other point I need to consider before reaching a conclusion??
Can any one suggest some remedies or tips to solve this trouble..??

REGARDS,
nandan

 

[catserveng]

Your apparent problem could be the result of a number of issues, since you report that the system shares load fine in Manual, likely you are looking in the right area.

So the first question is, did the system work fine before but now doesn't? I'm assuming this is an older system as governors with speed settings adjustment motors is fairly old technology.

What kind of governors on what kind of prime movers? What type of system is your PMS? Woodward, PLC based or some other type?

Load sharing on larger units with hydramechanical governors using speed setting motors can seem to have a fairly slow response characterisitic, and some load management systems can overdrive the speed setting and end up with load instability. How you correct that really depends on what system you are using, so getting some details from you would be helpful. Usually the load management system uses a small pulse to change the speed setting, the PMS system may be sending too large a pulse, could be too long or just sending too fast for the governor and fuel system to respond correctly.

Also depending on what governor you are using, over time the speed adjust mechanism will wear, and constant adjustments will end up not hitting the speed setpoint you want. How old is your system and has any recent work been done on the governors? Same issues with the speed settings motors themselves, as they age they don't respond as they should either due to mechanical or electrical problems.

Some more details from you about your system will likely get you some better answers.

Regards, MikeL.