It is now widely understood that Distributed Energy Resources (DER) cannot be treated under the "fit and forget" approach, but they should be controlled in order to add support to the network. The basic idea is to regard distribution networks as "active networks" in contrast to passive appendices. In fact, the provision of support to transmission network operation by active distribution networks is considered as a viable possibility. Control can be basically exercised by exploiting the power electronic converters used to interconnect most types of DER. Since DER are mostly inertialess or decoupled from the network, power electronics are used to mimic the behavior of traditional thermal machines using equivalent "droop" techniques. The panel aims to discuss the development of these techniques for parallel connected DER in both interconnected and islanded distribution network operation (microgrids) and their application to provide frequency/voltage control also considering the characteristics of distribution networks.