Flying capacitor multilevel PWM converter based UPFC

A unified power flow controller (UPFC) based on the flying capacitor (FC) multilevel voltage-source converter (VSC) topology with phase-shifted sinusoidal pulse-width modulation (PWM) control is presented. This converter allows higher power handling, potentially lower power loss, lower harmonic distortion and hence less filtering requirements when compared with the typical two-level counterpparl. The series converter injects a voltage with controlled magnitude and phase, to control the activelreactive power flow in a transmission line. The shunt converter absorbs/ supplies active power demanded by the series converter to maintain a constant DC link voltage, also providing independent reactive support to the network. A coniplete model of the proposed UPFC system is shown and control circuits are described in the synchronous d-q frame. Finally, simulation results are provided to confirm the robustness of the proposed system.