Can anyone direct me to a publication that describes how the kW loadsharing is established when synchronous machines (momentary) driven by a flywheel are running in parallel operation mode?
I realize this does not deal with Motor Testing but the know-how and know-how-not within this community encourages me to give it a try.
Arie Mol

Woodward Governor understands this process better than anyone I know of. Here's a link to their publications webpage, I bet you can find something there: http://www.woodward.com/pubs/p...m?web_section=engine

We were having trouble with 3 parallel generators fighting each other- they would start to oscillate and become unstable to the point where one would kick offline. We couldn't adjust it out. We run Woodward governors and had one of their techs out. I believe it turned out to be a droop adjustment that finally cured the fighting. It's interesting stuff. The speed controllers get better all the time.

Synchronous machines running in parallel (with rotor fields energized) will remain in synchronism provided they don't exceed a critical difference in rotor angle (corresponds to a critical transmitted torque). Imagine the two rotors are attached to each other by a spring... they will move together as long as you don't exceed the breaking strength of the spring. Let's say only one of the generators has a mechanical load connected... that generator rotor will start to lag compared to the other. Motor action in the lagging-angle generator combined with generator action in the leading-angle generator tend to keep them together in synchronism. Kinetic energy of the flywheels is converted to work to supply the load (which may include friction) as you alluded to and speed of both will gradually decrease.

For the two rotors connected together electromagnetically in synchronism (like a system of two masses connected together by one spring), if you apply a rapidly-changing high magnitude torque (force) to one of the rotors (masses), then you can get a high magnitude oscillating response at the resonant frequency which can challenge the critical transmitted torque (spring strength).

It's not clear exactly what scenario you are talking about. Two separate flywheels? Both machines deenergized and coasting ? Mechanical loads on both ? What was going on before/after this momentary period ? Are these rod drive motor generators?

This message has been edited. Last edited by: electricpete,

Since I talked about the possibility of oscillations, I should have said that of course the machines might trip if the oscillations are severe - depends on the scenario.

Problem solved.
Surprisingly in the end: reactive load sharing adjustment of digital controller was incorrect.
Thanks for responses!
Arie Mol
Rotating Equipment Consultant
NL