Modelling, Analysis and Control of a Power Flow Controller for AC-DC Meshed Grids

This paper extends the concept of the Power Flow Controller (PFC), initially developed for DC meshed grids, to hybrid AC/DC meshed grids. The coexistence of AC and DC power flows and the grid’s complex topology present significant modeling and control challenges. To address these, a bi-linear state-space model of a modular PFC integrated into an AC/DC meshed grid is derived. By introducing an appropriate change of variables, a formal analysis of its steady-state trajectories is given, revealing degrees of freedom and formal conditions for their existence. A particular choice of steady-state is formulated, leading to a constant equilibrium, thus a bilinear time-invariant model in error coordinates. A preliminary control law is proposed that renders this equilibrium globally asymptotically stable. Simulation results illustrate the effectiveness of the proposed approach.