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Analysis of consensus-based active power sharing with respect to network topology in islanded microgrids

Abstract:

A key objective to be fulfilled by distributed voltage source inverters working in parallel in islanded MicroGrids (MGs) is to ensure active power sharing while keeping the frequency at a desired setpoint. Recently, consensus-based control techniques have been applied at the secondary control level for active power sharing while correcting the frequency deviation that the droop control implemented at the primary control level introduces. To this end, inverters work in a cooperative way by sharing their own corrective action with their neighbors over a digital communication network. The contribution of this paper is to analyze how changes in the network topology affect the consensus-based active power sharing control goal. In particular, the analysis focuses on the network structure in terms of adjacency, that is, in terms of the number of connections that each node has. The theoretical analysis based on graph theory provides results that indicate the pattern that steady-state active power values will follow according to the network structure. Numerical examples are used to illustrate the theoretical results, and select simulations on a low-scale MG complete the analysis. The paper results provide insight into the existing design tradeoff between power sharing accuracy and number of network connections.