  One of the major challenges of voltage stabilization in converter-based DC
microgrids are the multiple interacting units displaying intermittent supply
behavior. In this paper, we address this by a decentralized scalable,
plug-and-play voltage controller for voltage-source converters (VSCs) at
primary level. In contrast to existing approaches, we follow a systematic and
constructive design based on port-Hamiltonian systems (PHSs) which does neither
require the heuristic proposition of a Lyapunov function nor the computation of
auxilliary variables such as time-derivatives. By employing the Hamiltonian
naturally obtained from the PHS approach as Lyapunov function and using the
modularity of passive systems, we provide sufficient conditions under which the
designed VSC controllers achieve microgrid-wide asymptotic voltage stability.
Integral action (IA), which preserves the passive PHS structure, robustifies
the design against unknown disturbances and ensures zero voltage errors in the
steady-state. Numerical simulations illustrate the functionality of the
proposed voltage controller.
