Behavior of Three-Phase Inverters under Grid Faults Explained from a Geometric Perspective

The aim of this work is to analyze the dynamic behavior of inverters powered by renewable energy sources (RES) operating under grid faults by means of a geometric point of view. To this purpose, a three-phase grid-connected inverter subject to voltage sags is analyzed. First, the mathematical equations that describe its electrical model under voltage sags are given in the complex form of the transformed Park components. Second, simulations results show the resemblance between the curve depicted by the transformed Park components of the injected currents in the complex plane and well-known geometric curves. Finally, the geometric-based approach is used to describe easily the dynamic behavior of grid-connected inverters under voltage sags. This new approach could be used to propose new control techniques to achieve fault ride-through (FRT) capability of three-phase inverters.