A Novel Adaptive Hierarchical Control Structure for Inverter Based DGs under Microgrid Dynamics

Microgrid is a distribution system consisted of loads and Distributed Generators (DGs) which are operating as a single power system to supply local area loads. DGs can provide various environmental and economical benefits but their presence in network poses great technical challenges in control, stability and protection sides which become a noticeable issues associated with the growing penetration of DGs in recent years. Power electronic interfaced DGs are of especial concern in microgrid control side as their control systems play a principal role in the DGs behaviors and subsequently microgrid stability. In this paper a hierarchical structure for multimode control system of inverter based DGs is presented which adaptively switches between Voltage Source Controller (VSC) and Current Source Controller (CSC) strictures according to network requirements during pre-and post-contingency conditions. The proposed system is communication based and assisted by Microgrid Central Controller (MGCC) as a tertiary control level through communication channels.