A study on the line-interactive UPS using the series voltage compensator

This paper presents a three-phase line-interactive uninterruptible power supply (UPS) system with series-parallel active power-line conditioning capabilities, using synchronous reference frame (SRF) based controller, which allows an effective power factor correction, source harmonic voltage compensation, load harmonic current suppression and output voltage regulation. The three-phase UPS system consists of two active power compensator topologies. One is a series active compensator, which works as a voltage source in phase with the source voltage to have the sinusoidal source current and high power factor under the deviation and distortion of the source voltage. The other is a parallel active compensator, which works as a conventional sinusoidal voltage source in phase with the source voltage, providing to the load a regulated and sinusoidal voltage with low total harmonic distortion (THD). The control algorithm using SRF method and the active power flow through the line-interactive UPS systems are described and analytically studied. The simulation results are depicted in this paper to show the effect of the proposed algorithms.