Significance of parallel operation of generators

In power plants the generators or alternators of smaller ratings are found to be operated in parallel instead operating of a single large generator capable of supplying the maximum demand on the system. These smaller generating units can be run singly or in various parallel combinations to suit the load demand. The importance of operating the power station in such a manner is
given by the below mentioned points.

High efficiency

The load on the power system is not always constant and it continuously varies with time to time as can be observed from a daily load curve. The generators operate at maximum efficiency when they are delivering their rated capacity. If a large single generator is employed to supply all the load demands it will have maximum efficiency at the peak demand and poor efficiency at all the lighter loads. Whereas if multiple number of generators are operated in parallel then the smaller units can be operated under light load conditions and can be substituted with larger units as the demand increases. 

Uninterrupted service

The event of break down in a power station having a single generator leads to complete shutdown of the entire station. This can be avoided by using the parallel operation, since if one of the generators fails the other generators will continue to supply the load demand. 

Ease of maintenance and Repair

The generators are inspected periodically for any possibilities of repairs or breakdowns. This can be easily done by isolating the generator under consideration while others continue to operate.

Increasing the generating capacity

The usage of electricity is increasing day by day and hence the load on the power system increases. This necessitates the need for additional generating capacity. This can be achieved by adding the generators in parallel as the demand increases.