ANALYSIS OF INRUSH CURRENT MITIGATION TECHNIQUES FOR LINE INTERACTIVE UPS SYSTEM

Abstract

Survey result suggest that 92% of interruption at industrial facilities is voltage sag related. Unexpected voltage or outage event interrupt the operation of manufacturing processes or even lead to equipment damages there for voltage compensation technique is used to maintain the desired load voltage, during voltage compensation technique there is chance of high inrush current. 1-lere scheme is provided to mainly mitigate the inrush current in transformer. Desired load voltage obtained from uninterrupted power supply system . Load transition from utility grid to uninterrupted power supply (UPS) takes 1 to 5ms so the start up process of UPS can cause significant inrush current phenomenon on the load transformer due to magnetic saturation. The inrush current could result in reduced line voltages and even trigger the UPS's overcurrent protection. To prevent the inrush current, a flux linkage offset compensation technique to be used which is based PWM with unipolar switching design to regulate the flux linkage of the transformer. The proposed technique can provide a very smooth and faster transition without the risk of inrush current for critical loads under power outages and voltage sags.