Design of Controller for Hybrid UPS with Energy Storage System Function Author Oh, Jin Hong School of Electrical Engineering and Computer Science, Graduate School of Chungbuk National University Cheongju, Korea

Design of Controller for Hybrid UPS with Energy Storage System Function Author Oh, Jin Hong School of Electrical Engineering and Computer Science, Graduate School of Chungbuk National University Cheongju, Korea

 A thesis for the degree of Master in August 2018

Abstract
With the active technological development of modern communication systems, advanced medical equipment, advanced living facilities, and emergency systems that requires high-quality energy are more and more widespread used in everyday life, which require more reliable, efficient, and uninterrupted electricity supply. Due to increase of these critical loads, a power supply with high quality and reliability is more important than ever. Consequently, Uninterruptible Power Supply(UPS) has recently experienced a growing demand. According to the International Electrotechnical Commission Standard IEC 62040-3, the UPS systems are categorized into on-line UPS, off-line UPS, line interactive UPS according to the energy flow direction under normal utility condition. Among them, The on-line UPS is receiving more intention from the researchers and engineers because of its outstanding capability of suppressing grid frequency variation, voltage irregularity and other power issues. However, because the stored energy of UPS battery is used only when these issues happen, battery utilization rate is very low. Therefore, hybrid UPS that integrates ESS with an on-line UPS has recently developed. Unlike the conventional UPS, hybrid UPS can increase battery utilization rate by using the stored energy of battery when the grid is under normal operation. whereas when the grid fails, hybrid UPS has to supplies emergency power to critical loads. Therefore, transient voltage across the DC-link that could affect the power quality of critical loads can occur during mode transition. this paper addresses new operation strategy of three phase hybrid UPS with Energy Storage System(ESS) function to minimize the transient voltage across the DC-link. PSCAD/EMTDC software is used to verify validity of the proposed operation scheme.

LINK
https://www.mediafire.com/file/lyxxcnyvv9nbwrl/Design_of_Controller_for_Hybrid_UPS_with_Energy_Storage.pdf/file