Experimenting with open source Switch, found that the system will extract itself into groups is therefore Microgrids Virtual frequency of the oscillations occur little Gen.
Switch to experiment, open source is found, the system will separate themselves into groups Virtual Microgrids such a frequency of the swing is slightly Gen.
Experiment on Switch at source, it is found that the system to distinguish themselves in groups Virtual Microgrids, as shown in the picture, there will be the frequency of Gen born swing slightly.