Synchronization process

There are five conditions that must be met before the synchronization process takes place. The source

(generator or sub-network) must have equal line voltage, frequency, phase sequence, phase angle, and

waveform to that of the system to which it is being synchronized.

 

Waveform and phase sequence are fixed by the construction of the generator and its connections to the system.

During installation of a generator, careful checks are made to ensure the generator terminals and all control

wiring are correct so that the order of phases (phase sequence) matches the system. Connecting a generator

with the wrong phase sequence will result in a short circuit as the system voltages are opposite to those of the

generator terminal voltages.

 

The voltage, frequency and phase angle must be controlled each time a generator is to be connected to a grid.

Generating units for connection to a power grid have an inherent droop speed control that allows them to share

load proportional to their rating. Some generator units, especially in isolated systems, operate with isochronous

frequency control, maintaining constant system frequency independent of load.