Experimental Validation of Nonlinear Control for a Voltage Source Converter

In this brief, we consider reactive power and DC voltage tracking control of a three-phase voltage source converter (VSC). This control problem is important in many power system applications including power factor correction for a distribution static synchronous compensator (D-STATCOM). Traditional approaches to this problem are often based on a linearized model of the VSC and proportional-integral (PI) feedback. In order to improve performance, a flatness-based tracking control for the VSC is proposed where the nonlinear model is directly compensated without a linear approximation. Flatness leads to straightforward open-loop control design. A full experimental validation is given as well as a comparison with the industry-standard decoupled vector control. Robustness of the flatness-based control is investigated and setpoint regulation for unbalanced three-phase voltage is considered.