In this research, the authors analyze the
protection behavior during power system restoration. The
bottom-up network restoration is done with the help of a blackstart
unit and concludes with a biogas plant taking over the
island. The focus of this paper is to evaluate the behavior of
protection devices, and to check their selectivity, sensitivity and
speed during different network restoration stages. The research
is done in two parts: In study case I, a protection investigation
is performed based on a short-circuit analysis of the complete
microgrid. In study case II, the dynamic behavior of the power
plant along with the voltage and frequency protection of
distributed energy resources is considered. At the end of the
investigation, recommendations for the restoration process in
islanding grids are given with regards to the protection concept
considering system stability to support automated bottom-up
restoration. The results are useful for distribution system
operators to design their protection concepts for their grid
operation in more flexible ways especially considering islanded
operations.