Maximum power

[todd066]

At what angle difference when Synchronizing a generator to the grid is the power (watts) the greatest?

 

[dpc]

At the maximum power transfer angle.

 

[todd066]

YOu might have to simplify that for me. I have been working in micro-electronics for the past 16 years. The last power course I took was too far back to remember.

 

[davidbeach]

Then you will probably have to ask your question in a longer form that indicates what you do understand and what you don't. Perhaps you should explain what you're trying to accomplish as that could help in understanding what kind of answer would be useful.

 

[todd066]

I am trying to understand some of the principles of sychronizing a generator to the grid. I understand that my maximum current draw would be if the generator were synched just behind the grid. The current between the two would be maximum while the generator attempts to "catch up" to the grid. Is maximum power then delivered at the point of synching to the grid or some other point during the process?

I would tell you more of what I don't know but the post would be way too long. Thanks for the help.

 

[davidbeach]

Maximum power and maximum current are not the same thing. 180[°] would result in the maximum current.

 

[electricpete]

Beyond max power angle, a pole slip occurs - that is not a good thing.

It is not an objective to maximize power or current at the time of synchronization. Typically we try to match angles closely, erring slightly on the side of generator angle lagging supply angle to avoid reverse powering the generator.

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[alehman]

todd066,
Following what David and Electripete said you normally synchronize at close to 0 phase angle. This minimizes disturbance to the system and impact on the machine, and results in little power flow right away. Once on-line, then the throttle is advanced to load the generator. As you add more power, you will eventually reach the maximum prime mover capacity or maximum power angle, whichever comes first.

Alan
----
"It’s always fun to do the impossible." - Walt Disney

 

[rbulsara]

todd066:

I think you are mixing up the phase angle difference during synchronization and the power angle at which maximum power transfer takes place. They are two different things.

The intent and attempt at the time of synchronizing is to keep the phase angle difference between the grid and generator as well as the power exchange between the two as close to zero as possible. Out of phase synchronization can lead to to heavy short circuit currents, avoiding which would be your prime objective.

The maximum power angle at which maximum power transfer would take place between the source and a load is the function of the system characteristics, which is something different and would be of concern only after the generators are on line.

Rafiq Bulsara

http://www.srengineersct.com

 

[electricpete]

Typically we try to match angles closely, erring slightly on the side of generator angle lagging supply angle to avoid reverse powering the generator.

That was a little off. Should have been:

Typically we try to match angles closely. Also we try to match frequencies, erring slightly on the side of generator frequency higher than supply frequency to avoid reverse powering the generator.

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[waross]

For day to day operations, many operators have no idea whatsoever what the power angle is and have no equipment to measure it. Sync at equal voltages, 0 degrees (12:00 o-clock) and slightly higher frequency. Open the throttle until max kW or max KVA is reached. Sure there is a power angle, but it is not known in many plants.

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