A bi-directional UPS with the performance of harmonic and reactive power compensation

This paper proposes a bi-directional uninterruptible power supply (UPS) with the performance of harmonics and reactive power compensation. The operation of the proposed UPS can be divided into two modes, such as active power filter (APF) mode and back-up power mode, as the state of power line source and the operation of the power converter. Especially, the improvement of transient response is considered, so a new, simple and precise calculation method of reference current for harmonics and reactive power compensation technique is proposed and the control scheme of back-up power mode is based on the instantaneous voltage and current control technique. The system model and control algorithm is described and analyzed and the transient performance is verified by the simulation and experimental results