I got in trouble with power synchronizing issue between the shore and vessle’s one.
The condition is this.
1. Operating the generator power in vessle with 440v 60hz 80kw.
2. About to sync it with shore power with 440v 60hz.
3. I speed down the generator under 60hz and also down the voltage a little bit of vessle.
4. The sync relay operate in good conditon. So the circuit breaker of shore power engaged smoothly.
5. Now i would transfer the load from vessle to shore, so down the speed generator in vessle.
6. But doesn’t transfer the power to shore. Not even a single killowatt.
7. It seems like parrallel inoperation but it doesn’t
8. Now i adjust the speed of generator, the indicator of frequency indicate downward. So, i think thet aren’t sync now.

what would be a problem?
Anyone who has some experiences like that, please share some knowhows….

i just think its problem could belongs to the power from shore and its device…

 

Have you ever had problems with this particular shore power before?

DO YOU KNOW FOR CERTAIN THE GENERATOR ACTUALLY CLOSED AND REMAINED CLOSED AFTER THE SYNCHRONIZATION WAS "COMPLETE"?

What is the source of the shore power? Does it come from a large grid or another single generator, or perhaps a couple of small generators?

If the source of the shore power was from a single generator AND the generator's prime mover governor was not in Isochronous Speed Control Mode then it's possible you could experience the problem you are attempting to describe.

If the source of the shore power was from a "large" grid with many other generators and their prime movers (of various capacities) then it's not likely the shore power breaker was actually closed when you tried to lower the load on the vessel's generator.

 

Yes. It was to large grid. The indicator of breaker was “close”. So i asked cause of so weird.
Anyway thank you for your reply.

 

Have you ever had problems with this particular shore power before?

 

Yes, the same location. but i don't have any clue of the problem from the shore power system.

 

There are lots of posts on Control.com about the synchronizing process--all of them presume the generator being synchronized is a three-phase synchronous generator.

What is the prime mover of the vessel generator?

Is the vessel generator a synchronous or induction generator? Single-phase, or three-phase?

Quote from the original post:

5. Now i would transfer the load from vessle to shore, so down the speed generator in vessle.
6. But doesn’t transfer the power to shore. Not even a single killowatt.
7. It seems like parrallel inoperation but it doesn’t
8. Now i adjust the speed of generator, the indicator of frequency indicate downward. So, i think thet aren’t sync now.

It's really difficult for me to imagine a situation where the vessel synchronous generator was actually synchronized to a large grid that is operating at a stable frequency.

A synchronous generator's speed and frequency are DIRECTLY related--meaning that when the generator IS NOT synchronized with other generators increasing the speed of the prime mover driving the generator (and therefore the generator) will increase the frequency of the generator, and reducing the speed of the prime mover driving the generator (and therefore the generator) will decrease the frequency of the generator. Full stop. Period.

When a generator is synchronized to a grid with other generators and their prime movers, to reduce the load on a generator one reduces the energy flow-rate into the generator's prime mover--BUT when it's synchronized to the grid with other generators the speed of the generator and prime mover are controlled by the frequency of the grid. NEITHER the generator or the prime mover speed can change or will change when the energy flow-rate into the generator prime mover--the speed(s) are controlled by the frequency of the grid.

You said you decreased the speed of the vessel generator to transfer the load from the generator to the shore power (grid). You said the load of the vessel generator didn't change. Then you said adjusted the speed of the vessel generator and the generator frequency indicator decreased. This is EXACTLY how a synchronous generator that IS NOT SYNCHRONZED TO A GRID would behave when it's prime mover's speed (and therefore the generator's speed) is decreased. (NOTE: I'm presuming the generator is a synchronous generator (because you said you could adjust the voltage of the generator.)

I presume you were trying to shut down the prime mover driving the vessel generator by having the load of the vessel being powered by the shore/grid power. You would do that by synchronizing (a synchronous generator) to the shore/grid power and then reducing the energy flow-rate into the vessel generator's prime mover. THE VESSEL GENERATOR WILL NOT SLOW DOWN, nor will the vessel generator prime mover slow down. Their speed is controlled by the frequency of the shore/grid, and an 80kW generator ain't gonna change the shore/grid frequency.

If the vessel generator was powering the vessel then the vessel generator's breaker would be closed. AND it would seem you were trying to synchronize across another "tie" breaker, and the tie breaker WAS NOT closed. (I was assuming something different when I asked about the vessel generator main breaker. My bad.)

Without knowing a LOT MORE about the electrical system aboard the vessel, the prime mover and type of prime mover governor driving the generator) and the shore/grid tie electrical system there's very little I can add to this thread. Except to state that while the vessel generator's main breaker was closed the tie breaker to the shore/grid system WAS NOT closed. I don't know where you obtain the signal to know the status of the shore/grid tie breaker, but it would seem it's not working correctly because the vessel generator was not operating in parallel with the shore/grid power system (as you stated in your original post).

Then there's the whole thing of whether or not the vessel generator's prime mover was operating in Droop Speed Control mode or Isochronous Speed Control mode. It should have been in Isochronous Speed Control mode to control vessel frequency as vessel load changes, and transition to Droop Speed Control as soon as the shore/grid tie breaker closed. It may have done that, but it was not actually synchronized (operating in parallel with) the shore/grid power system because the shore/grid power tie breaker was not actually closed. (Trying to run a small generator (80kW is small) in Isochronous Speed Control mode when synchronized to (operating in parallel with) a large shore/grid power system would be pretty unstable, probably. But, again, there's just too much we don't know about the system and the vessel and the shore/grid power system. What we do know is (as you wrote) the vessel generator WAS NOT synchronized to (operating in parallel with) the shore/grid power system--regardless of what the tie breaker status indication was.

 

Hi

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