The paper presents a unified power flow controller (UPFC) based on the flying capacitor (FC) multilevel voltage source converter (VSC) with phase-shifted sinusoidal PWM control. The topology allows high power handling, low power loss, low harmonic distortion and hence less filtering requirement. The series converter injects a voltage with controlled magnitude and phase to control the active/reactive power flow in a transmission line. The shunt converter absorbs/supplies active power demanded by the series one to maintain a constant DC link voltage, providing also independent reactive support to the network. A complete model in the synchronous d-q frame is presented and control circuits are described. Finally, simulation results are provided to confirm the robustness of the proposed system.
- multilevel converter
- unified power flow controller
- multilevel voltage source converter