What Is Island Operation Mode?

One or more diesel generators operating without connection to the grid is known as islanded mode of operation. Parallel working generators can achieve better efficiency at partial load. An islanded power plant for the primary power supply of an isolated community will typically have at least three diesel generators, any two of which are rated to carry the required load.
The generators can be electrically connected together through a synchronization process. Synchronization involves matching the voltage, frequency and phase before connecting the generators to the system. Failure to synchronize before connection can result in high short circuit currents or wear on the generators or their switchgear. The synchronization process can be done automatically by an auto-synchronizing module, or manually by an operator under guidance. The auto-synchronizer will read the voltage, frequency and phase parameters from the generator and bus voltages while regulating the speed through the engine governor or ECM (Engine Control Module).
The load can be shared between the generators operating in parallel through load sharing. Load sharing can be achieved by using a drooping speed control controlled by the generator frequency while it constantly adjusts the engine fuel control to transfer load to or from the remaining source. The diesel generator will take on more load when the fuel supply to its combustion system increases, and release load if the fuel supply decreases.