In the parallel operation of synchronous generators, the incoming generator must have a slightly higher speed than the connected generators to avoid phase differences upon synchronization. If both generators operate at the same speed, a phase difference occurs due to the electrical counter torque not matching the input mechanical torque, leading to reverse current flow and potential activation of the reverse power trip. The connected generator will slow down as it takes on load, while the already loaded generator will speed up, resulting in out-of-synchronization conditions.
PREREQUISITESElectrical engineers, power system operators, and anyone involved in the operation and synchronization of synchronous generators will benefit from this discussion.
how it will cause phase difference when the speed will be same? can you please elaborate?Rippetherocker said:Because as soon as the generator is connected it will take some load and will try to slow down and the already loaded gen. will try to speed up. If both had the same intial speed this will result in a phase difference after connection. A reverse current will flow into the new gen. and activate the reverse power trip.
thank you..FOIWATER said:The speed will not be the same. When the generator is connected it will provide power to the system and the electrical counter torque on the shaft won't match the input mechanical torque. The machine will slow down. The other machine will speed up, since it takes less load now. With them running at different speeds they will be out of synch. That causes the phase difference. I didn't really add anything to the first response but I think he is pretty clear. Does it make sense?