Unified power flow controller

It uses a pair of three-phase controllable bridges to produce current that is injected into a transmission line using a series transformer.

The UPFC uses solid state devices, which provide functional flexibility, generally not attainable by conventional thyristor controlled systems.

[3] The main advantage of the UPFC is to control the active and reactive power flows in the transmission line.

[6] It uses a high-frequency isolated DC-to-DC converter cascaded with a controllable full-bridge inverter that creates a small bipolar voltage in series with the line.

The partial power processing leads to increased system efficiency and use of derated components.