Robust stability analysis of DC microgrids with constant power loads

摘要

This paper studies stability analysis of DC microgrids with uncertainconstant power loads (CPLs). It is well known that CPLs have negative impedanceeffects, which may cause instability in a DC microgrid. Existing works oftenstudy the stability around a given equilibrium based on some nominal values ofCPLs. However, in real applications, the equilibrium of a DC microgrid dependson the loading condition that often changes over time. Different from manyprevious results, this paper develops a framework that can analyze the DCmicrogrid stability for a given range of CPLs. The problem is formulated as arobust stability problem of a polytopic uncertain linear system. By exploitingthe structure of the problem, we derive a set of sufficient conditions that canguarantee robust stability. The conditions can be efficiently checked bysolving a convex optimization problem whose complexity does not grow with thenumber of buses in the microgrid. The effectiveness and non-conservativeness ofthe proposed framework are demonstrated using simulation examples.