Optimal isolated microgrid topology design for resilient applications

Abstract

Meshed microgrids have been used in a plethora of specialised applications that demand increased system resilience, from data centres to the international space station. When resilience maximisation is the desideratum, topology design is the fundamental factor determining the overall system performance. Very few published papers on this problem are found in literature and they take into consideration partial available topologies, or they fail to quantify resilience or assess microgrid stability. To address these gaps on microgrid topology planning (MTP), this paper proposes a holistic optimal topology design framework, comprised of six stages: (a) graph generator to extract all possible connected, non-isomorphic networks for a given number of nodes, (b) optimal asset positioning upon each generated graph using mixed-integer linear programming, (c) small-signal stability assessment and (d) post-outage flow matrix calculation for each microgrid to quantify repercussions from fault/damage of all interconnecting lines, (e) quantification of resilience metrics originally applied to distribution systems to assess vulnerability and criticality of each line, along with classic graph-theoretical indicators and finally, (f) aggregation of said metrics to rank the produced microgrid topologies. The proposed methodology is evaluated through detailed discrete simulations to assess its efficacy and the dynamic stability of the optimal microgrid topology.