manual synchronization

[babysitter]

Hi All,

If you miss the opportunity to manually sync when the scope needle is moving clockwise is it okay to immediately slow the prime mover down enough for the scope to rotate counter clockwise and sync in?

 

[esee135]

... If you watch the rotor angle during a synchronization your will notice that the close in response is a small signal phenomena. [P=Vt*Ef/Xs*sin(delta)]. The dynamic change in rotor angle damping post synchronization causes the power swing. Even good synchronizations can cause dynamic power swings of 60% nameplate MVA.

The frequency during synchronization is also noticed on the distributor valve of the governor at the instance of synchronization. This is very apparent on Woodward governors, where the speed error dynamic swing envelope causes gate movement.

The shockwave during an out of sync event is caused from the synchronizing torque of the generator acceleration/deceleration of the rotor to the 0 degree reference. In other words, I too would grunt loudly trying to rotate 200TONs immediately.

Perfect synch's will achieve 0MW and 0MQ upon sync. Deviation of the values means you have an offset in speed error or terminal voltage. A perfect sync will result in a near silent breaker close (you should only hear the operating mechanism). Always account for the GSU tap ratio in the sync running/incoming bus PT signal, depending on having a LS-GCB or HS-GCB.