  As the number of converter-based renewable generations in the power system is
increasing, the inertia provided by the synchronous generators is reducing,
which in turn is reducing the stability margins of the power system. In order
to assess the large-signal stability, it is essential to model the wind power
plant connections accurately. However, the actual EMT models are often
unavailable, black-boxed, or computationally too heavy to model in detail.
Hence, simplified reduced-order models (ROMs) resembling the actual system
behaviour have gained prominence in stability studies. In this regard, an
improved WT ROM was proposed to investigate large signal stability during
unbalanced grid faults. The methodology presents a systematic way to model the
coupled sequence components of the WT ROM for various grid faults. Based on the
studies carried out in this paper, it is observed that post unbalanced grid
disturbances the proposed WT ROM correctly tracks the angle and frequency, and
its trajectory is a good match when compared to a detailed simulation model in
PSCAD.
