Title: Robust stability analysis of DC microgrids with constant power loads,
Abstract: This paper studies stability analysis of DC microgrids with uncertain
constant power loads (CPLs). It is well known that CPLs have negative impedance
effects, which may cause instability in a DC microgrid. Existing works often
study the stability around a given equilibrium based on some nominal values of
CPLs. However, in real applications, the equilibrium of a DC microgrid depends
on the loading condition that often changes over time. Different from many
previous results, this paper develops a framework that can analyze the DC
microgrid stability for a given range of CPLs. The problem is formulated as a
robust stability problem of a polytopic uncertain linear system. By exploiting
the structure of the problem, we derive a set of sufficient conditions that can
guarantee robust stability. The conditions can be efficiently checked by
solving a convex optimization problem whose complexity does not grow with the
number of buses in the microgrid. The effectiveness and non-conservativeness of
the proposed framework are demonstrated using simulation examples.