joint synchronization

[odlanor]

after a load rejection, the system separates from the powerplant, but generators remain synchronized to busgeneration in speed no load.
1-will be possible to synchronize the busgeneration with system keeping all generators connected?
2 - Is it feasible?

 

[waross]

If there is a slight frequency error you may close in at the next time the sources are in sync. Best if the generator frequency is a little fast. You may have reverse power trips if the generator frequency error is on the slow side.
The main issue that I see is a case where you must adjust the speed of all generators in unison without any units lagging and then tripping on reverse power. A good load controller may do this. Old school, we used to do something similar with droop control.
We used to pick up loads with parallel generators in our little power plant. Often, unloaded groups of generators would be hit with overloads on closing. More difficult than just sync'ing.
At one site we had a motor that needed two generators in parallel to start. One gen-set had an electronic governor and the other had a hydraulic governor. We couldn't do it with a cold engine. The hydraulic unit had to be warmed up for 30 or 40 minutes before the oil was thin enough and the governor response fast enough to almost keep up with the electronic governor. But it was doable and we did it.
A digression I know, but compared to this, sync'ing a bus with unloaded parallel generators is almost as easy as turning on the kitchen light fixture.

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[odlanor]

you're talking about with manual synchronization adjustment of each generator?

 

[odlanor]

you're talking about with manual synchronization adjustment of each generator?
I am talking about joint synchronization of 4 x 80MVA-13.8kV generators in parallel.

 

[catserveng]

It is fairly common in systems I work with, typically 1-10 MW per unit, usually 2-6 units on the bus being paralleled back to grid. Most of the systems I am familiar with are based on the Woodward DSLC/MSLC controls, and when properly tuned will do the job quite well.

The size range of units you're working with is larger than I normally deal with, but I would expect the same controls could be applied to them as well, depending on their installed governing and AVR's.

Mike L.

 

[ScottyUK]

Most half-decent turbine controllers are capable of this. A lot depends on how well the application code has been written and how tight the governor control is, but in principle it is entirely possible. Bad loop tuning, or poor governor hardware, will make it more difficult.

 

[DTR2011]

Another option is available from SEL as an Engineered Solution:

SEL Auto Sync

I've seen many systems work and some with with problems, albeit it is generally due to poor initial tuning and set up, compounded with older AVR's and Governors.

I commissioned a system at an Ethanol plant a few years ago that had 2 utility lines and 4 2 MW Gens. The system could peak shave or island and come back with either or both utility feeds. It was new and properly designed from the beginning. The generator experts had their end of things worked out in a few days.

 

[LionelHutz]

It should be possible. How did you get the system on-line before the trip?

If you're unsure about any of this then you need to hire some professional and experienced help. Simply following a few short paragraphs from a forum telling you how to line synchronize 320MVA of genset sounds like a bad idea.

 

[odlanor]

LionelHutz,

- You synchronize 1st generator. When loading begins you synchronize another generator that participate also with loading.

You are right. This hydropower plant must be connected to transmission line system of a big utilitity. Settings of synchronization are very severy.
Ii seems to me there is no example for syncronization joint in this case.

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