Patent ID: 7932637

Claim:
A method of controlling distributed energy resources, the method comprising: operating a microsource in a grid mode in which the microsource is connected to a utility grid, wherein the microsource is located in a microgrid and is configured to deliver a power P 1 at a frequency ω 1 , wherein during operation in the grid mode the frequency ω 1 is approximately equal to a first frequency and the power P 1 is approximately equal to a first power, and wherein the first frequency is an operating frequency of the utility grid; and transferring the microsource from the grid mode to an island mode such that the microsource is disconnected from the utility grid, wherein the transferring causes a frequency change such that the frequency ω 1 changes to a second frequency and a power change such that the power P 1 changes to a second power; wherein the microsource has a slope switch frequency, wherein the frequency change occurs at a first rate with respect to the power change while the frequency ω 1 is less than the slope switch frequency, and wherein the frequency change occurs at a second rate with respect to the power change while the frequency ω 1 is greater than the slope switch frequency.