Patent ID: 7521825

Claim:
A method of operating an interface switch associated with a microgrid, the method comprising: receiving an AC voltage V at an internal terminal of the interface switch from a microsource bus, wherein the internal terminal of the interface switch is electrically connected to the microsource bus, and further wherein an external terminal of the interface switch is electrically connected to a supply bus having an AC voltage Ē; determining a voltage difference between the AC voltage Ē and the AC voltage V when the interface switch is in an open position; determining a relative phase angle δ EV between the AC voltage Ē and the AC voltage V while the interface switch is in the open position; closing the interface switch upon detection that the voltage difference between the AC voltage Ē and the AC voltage V is less than a first predetermined threshold, the relative phase angle δ EV between the AC voltage Ē and the AC voltage V is less than a second predetermined threshold, and the AC voltage Ē leads the AC voltage V ; and importing electrical power from the supply bus to the microsource bus through the closed interface switch.