Unified power flow controller (UPFC) based on chopper stabilized multilevel converter

A system of class B choppers equalizes the DC voltages of the back-to-back multilevel converters of the UPFC thus removing the constraint that the voltages of the series and the shunt converter must operate at a fixed ratio. This allows the UPFC to operate with independent controls over the real power and the reactive powers on both sides. The claims are substantiated by digital simulations and laboratory experiments.