  Distributed energy resource (DER) frequency regulations are promising
technologies for future grid operation. Unlike conventional generators, DERs
might require open communication networks to exchange signals with control
centers, possibly through DER aggregators; therefore, the impacts of the
communication variations on the system stability need to be investigated. This
paper develops a cyber-physical dynamic simulation model based on the
Hierarchical Engine for Large-Scale Co-Simulation (HELICS) to evaluate the
impact of the communication variations, such as delays in DER frequency
regulations. The feasible delay range can be obtained under different parameter
settings. The results show that the risk of instability generally increases
with the communication delay.
