Islanding islanding refers to the condition in which a distributed generator (dg) continues to power a location even though electrical grid power from the electric utility is no longer present. islanding can be dangerous to utility workers, who may not realize that a circuit is still powered, and it may prevent automatic re-connection of devices. for that reason, distributed generators must detect islanding and immediately stop producing power; this is referred to as anti-islanding. the common example of islanding is a grid supply line that has solar panels attached to it. in the case of a blackout, the solar panels will continue to deliver power as long as irradiance is sufficient. in this case, the supply line becomes an "island" with power surrounded by a "sea" of unpowered lines. for this reason, solar inverters that are designed to supply power to the grid are generally required to have some sort of automatic anti-islanding circuitry in them. in intentional islanding, the generator disconnects from the grid, and forces the distributed generator to power the local circuit. this is often used as a power backup system for buildings that normally sell their excess power to the grid. intentional islanding describes the condition in which a microgrid or a portion of the power grid, which consists of a load and a distributed generation (dg) system, is isolated from the remainder of the utility system. in this situation, it is important for the microgrid to continue to provide adequate power to the load. under normal operation, each dg inverter system in the microgrid usually works in constant current control mode in order to provide a preset power to the main grid. when the microgrid is cut off from the main grid, each dg inverter system must detect this islanding situation and must switch to a voltage control mode. in this mode, the microgrid will provide a constant voltage to the local load. the grid was disconnected at 0.5 s, and this event was detected at 0.50256 s. index terms:- distributed generation (dg), grid-connected operation, intentional-islanding operation, islanding detection, load shedding, synchronization.