Extended secondary control with grid-forming inverters for communication-free island operation

To ensure a communication-free island grid operation, an approach consisting of a secondary control with grid-forming inverters and state machines implemented within smart meters is needed. The approach has already been proposed in literature. However, further extensions were found to be necessary to address some drawbacks of the presented approach, like high power peaks and long-lasting overload states of inverters. This publication introduces these extensions and presents the advantages, compared to the originally presented secondary control with grid-forming inverters, by showing different RMS simulation cases which are carried out in PowerFactory.