Kron reduction methods for plug-and-play control of ac islanded microgrids with arbitrary topology
For control engineers designing decentralized controllers for microgrids, this work removes a topological restriction of prior methods, enabling application to general interconnection networks.
The paper extends a scalable plug-and-play control algorithm for AC islanded microgrids to handle arbitrary topologies by introducing an approximate Kron reduction method that preserves the asymptotic periodic behavior of electric signals, validated on a 21-bus IEEE test feeder.
In this paper, we provide an extension of the scalable algorithm proposed in (Riverso et al., 2015) for the design of Plug-and-Play (PnP) controllers for AC Islanded microGrids (ImGs). The method in (Riverso et al., 2015) assumes DGUs are arranged in a load-connected topology, i.e. loads can appear only at the output terminals of inverters. For handling totally general interconnections of DGUs and loads, we describe an approach based on Kron Reduction (KR), a network reduction method giving an equivalent load-connected model of the original ImG. However, existing KR approaches can fail in preserving the structure of transfer functions representing transmission lines. To avoid this drawback, we introduce an approximate KR algorithm, still capable to represent exactly the asymptotic periodic behavior of electric signals even if they are unbalanced. Our results are backed up with simulations illustrating features of the new KR approach as well as its use for designing PnP controllers in a 21-bus ImG derived from an IEEE test feeder.