Effects of Poor Synchronization
Use Synchronization unit in the power plant
In power plant the synchronization unit is mounted on the plant control room and on Generator Control Panel (GCP) at the Turbine building. In a power plant the synchronization unit can be used to synchronize the Turbo Alternator (TA) to the Grid power supply and to synchronize the Diesel Generator with Class IV normal power supply for testing the diesel generators.
Turbo Alternator Synchronization
In the first case of TA synchronization with the grid power supply, there is a scope multiple synchronization breakers between the TA and grid. For example consider a power plant with single bus bar and single circuit breaker switching scheme (Normally this is not envisaged, there will be redundancy in busses as well as circuit breakers) as shown in below figure.
The generator is connected to the power system bus (Grid) through step-up transformer called Generator Transformer (GT). There are two circuit breakers to connect the generator to the power network i.e. one of the two circuit breakers has to be synchronized and closed. During plant start-up the circuit breaker near to the generator should be synchronized and closed and the other one will synchronized and closed after house load operation. Using two synchroscope is not cost effective so one synchroscope with complex circuit is preferred which includes selection of circuit breaker to be synchronized, selection the two voltages to be synchronized and providing synchronization permission to the corresponding circuit breaker. A micro-controller based control circuit provides better performance than normal relay logic.
Diesel Generator Synchronization
In a power plant diesel generator (DG) provides emergency power supply when the normal power supply fails. Till that time normally all DG’s will be idle but keeping idle may results in improper working at the time of need. So periodically the diesel generators are tested by operating them parallel with the normal power supply. This is done by synchronizing the diesel generators with normal power supply and closing the circuit breaker to connect. This process is strictly followed in nuclear power plant compared to fossil power plants where DG’s are their major emergency source to cool the reactor even after the plant in shutdown.