Various examples are directed to systems and methods for detecting an islanding condition at an inverter configured to couple a distributed generation system to an electrical grid network. A controller may determine a command frequency and a command frequency variation. The controller may determine that the command frequency variation indicates a potential islanding condition and send to the inverter an instruction to disconnect the distributed generation system from the electrical grid network. When the distributed generation system is disconnected from the electrical grid network, the controller may determine whether the grid network is valid.
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH/DEVELOPMENT
 This invention was made with Government support under Award Number DE-EE0006459 by the Department of Energy. The Government has certain rights in the invention.