Impact of active distribution networks on transient stability

The increasing penetration of distributed energy resources (DERs) has turned passive distribution networks into active, in turn affecting the dynamic behavior of the system. It is essential to investigate to what extent transmission system dynamics are affected by these changes. This paper aims at identifying the impact of active distribution networks (ADNs) on transient stability. The studies consider two main scenarios. In the first, same initial conditions are considered in an attempt to investigate the effect of ADN dynamics alone. In the second, prefault operating conditions are also varied in a realistic manner through generation of representative daily profiles for load and renewable generation. The impact of fault, ADN, and critical SG location is investigated. In addition, the response of DER control and protection to short and longer faults highlights how different aspects of transient stability are affected.