  This paper proposes a distributed secondary voltage control method based on
extended state Kalman-Bucy filter (ESKBF) and fast terminal sliding mode (FTSM)
control for the resilient operation of an islanded microgrid (MG) with
inverter-based distributed generations (DGs). To tackle the co-existence of
multiple uncertainties, a unified modelling framework is proposed to represent
the set of different types of disturbances, including parameter perturbation,
measurement noise, and immeasurably external variables, by an extended state
method. Kalman-Bucy filter is then applied to accurately estimate the state
information of the extended DG model. In addition, based on the accurate
estimation, a fast terminal sliding mode (FTSM) surface with terminal
attractors is designed to maintain the system stability and accelerate the
convergence of consensus tracking, which significantly improves the performance
of secondary voltage control under both normal and plug-and-play operation.
Finally, case studies are conducted in both MATLAB/Simulink and an experimental
testbed to demonstrate the effectiveness of the proposed method.
