Diesel Generator Island Operation Mode

Operating one or more diesel generators without being connected to the grid is known as islanding mode of operation. Working generators in parallel provide better efficiency at part load. An island power plant used as the main power source for an isolated community will typically have at least three diesel generators, any two of which are rated to carry the required load.
Generators can be electrically connected together through a synchronization process. Synchronization involves matching voltage, frequency and phase before connecting the generator to the system. Failure to synchronize before connection may result in high short-circuit current or wear and tear on the generator or its switching equipment. The synchronization process can be done automatically by the auto-sync module, or manually by a guided operator. The automatic synchronizer will read the voltage, frequency and phase parameters from the generator and bus voltage while regulating the speed through the engine governor or ECM (Engine Control Module).
Load can be shared between generators operating in parallel through load sharing. Load sharing can be achieved by using droop speed control controlled by the generator frequency, while it continuously adjusts the engine fuel control to transfer load to or from the remaining power source. A diesel generator will take on more load when the fuel supply to its combustion system increases, and release the load if the fuel supply decreases.