The paper describes an analytical large-signal model for unbalanced operation of the unified power flow controller (UPFC). This nonlinear, time-invariant model is expressed in terms of dynamic symmetric components, and it is validated on a benchmark power system example taken from the literature. The model is evaluated via simulations in unbalanced operation and during unbalanced (one phase to ground) faults. In both cases, it achieves a very good accuracy, in addition to a reduction in simulation time when compared with detailed time-domain models.