Towards a time-domain modeling framework for small-signal analysis of unbalanced microgrids

Small-signal analysis is one of the most frequently used techniques to assess the operating conditions of power systems. Typically, this analysis is conducted by employing a phasor-based model of the power network derived under the assumption of balanced operating conditions. However, distribution networks and, amongst these, microgrids are often unbalanced. Hence, their analysis requires the development of tools and methods valid under such conditions. Motivated by this, we propose a modeling approach for generic nonlinear and unbalanced three-phase microgrids, which allows to derive a small-signal model in a standard fashion. The approach is based on a time-domain decomposition of the electrical waveforms in positive and negative synchronous reference frames. The efficacy of the approach is demonstrated via application to an exemplary unbalanced microgrid.