• Title/Summary/Keyword: UPS inverter

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The Development and Experimental Evaluation of 100kVA Unified Power Quality Conditioner interconnected to the Li-Battery System (리튬 배터리를 연계한 100kVA UPQC 개발 및 성능시험)

  • Lee, Hak-Ju;Chae, Woo-Kyu;Park, Jung-Sung;Sohn, Jin-Man;Choi, Eun-Sik
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.26 no.10
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    • pp.102-110
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    • 2012
  • This paper propose the advanced topology of UPQC, its DC link is connected with Lithium battery, to compensate the momentary interruptions. The proposed system can be operated as UPS mode using the parallel inverter, which control the charge or discharge of battery, in case of the interruption. We dvelop 100kVA UPQC using the proposed topology to rise the power quality and the reliability of Microgrid. We verify its usefulness through voltage compensation test, UPS operation test and etc. using Microgrid test facility.

Robust Decoupling Digital Control of Three-Phase Inverter for UPS (3상 UPS용 인버터의 강인한 비간섭 디지털제어)

  • Park, Jee-Ho;Heo, Tae-Won;Shin, Dong-Ryul;Roh, Tae-Kyun;Woo, Jung-In
    • The Transactions of the Korean Institute of Electrical Engineers B
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    • v.49 no.4
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    • pp.246-255
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    • 2000
  • This paper deals with a novel full digital control method of the three-phase PWM inverter for UPS. The voltage and current of output filter capacitor as state variables are the feedback control input. In addition, a double deadbeat control consisting of a d-q current minor loop and a d-q voltage major loop, both with precise decoupling, have been developed. The switching pulse width modulation based on SVM is adopted so that the capacitor current should be exactly equal to its reference current. In order to compensate the calculation time delay, the predictive control is achieved by the current·voltage observer. The load prediction is used to compensate the load disturbance by disturbance observer with deadbeat response. The experimental results show that the proposed system offers an output voltage with THD less than 2% at a full nonlinear load.

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Static Switch Control of UPS with Active Filter Function (능동 필터 기능을 갖는 무정전전원장치의 정적 스위치 제어)

  • Hong, Hyun-Mun;Jeon, B.S.;Kim, J.G.;Lee, S.H.;Kim, J.S.;Min, Y.G.
    • Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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    • 2005.05a
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    • pp.406-408
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    • 2005
  • In this literature, when the utility line is normal, the Off-Line UPS operates as an active power filter to compensate the reactive power from a load, and when the utility line is in outage, the On-Line UPS opuates as in single phase inverter to supply an active and reactive power to the load. An additional static switch in UPS was used to decrease an transient state during these mode changes. And the result shows that the transient state disappeared.

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A study on the Noise Reduction of Uninterruptible Power Supply using Random PWM Method (Random PWM 기법을 이용한 무정전 전원장치의 노이즈 저감에 관한 연구)

  • Eom, Tae-Wook;Lee, Byung-Soon;Lee, Jae-Hak
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.28 no.11
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    • pp.100-105
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    • 2014
  • In this paper, Uninterruptible Power Supply(UPS) Inverter system using Carrier Frequency Modulated PWM (CFM-PWM) is proposed to reduced harmonics and electromagnetic noise. Power conversion of UPS system is executed by the ON-OFF operation of semiconductor switching devices. However, this switching operation causes the surge and EMI which deteriorate the reliability of the UPS system. This Problems improved by Random PWM switching method. The simulation results of the proposed system was compared with the system using conventional method using Matlab/Simulink. The results show that the output voltage and current harmonics of the proposed UPS system significantly decreased and spread into wide band area by the proposed Carrier Frequency Modulated PWM(CFM-PWM) method based on the Space Vector Modulation.

A Disturbance Observer-Based Load Current Estimation Method for Ups Inverter Applications (인버터응용을 위한 외란관측기에 의한 부하전류추정 방법)

  • Jang, Jae-Young;Lee, Kyo-Beum;Song, Joong-Ho;Choy, Ick;Yoo, Ji-Yoon;Choi, Ju-Yeop
    • The Transactions of the Korean Institute of Electrical Engineers B
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    • v.51 no.3
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    • pp.116-124
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    • 2002
  • Design and analysis of disturbance observer-based deadbeat control fur single-phase inverter applications are comprehensively presented in this paper. Load current can be estimated by disturbance observer, which is basically structured with the first order equation in this case and is regarded as a relatively simple method in comparison with conventional full-order Luenberger observer. Also, an inherent one-step delay problem appeared in the deadbeat control method is overcome by a simple prediction technique proposed. Output voltage dip is reduced by the feedforward control with the change rate of the estimated load current involved in the deadbeat current control loop. The proposed algorithms are verified by the respective simulation and experiment results.

The Improvement of Output Voltage of UPS Using a Parallel Control Method (병렬 제어기법을 이용한 UPS 출력 전압의 개선)

  • 成 炳 模;姜 弼 淳;朴 晟 濬;金 喆 禹
    • The Transactions of the Korean Institute of Power Electronics
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    • v.7 no.2
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    • pp.158-164
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    • 2002
  • This paper presents a proper parallel control method using a conventional control and a repetitive control for improving the output voltage waveform of uninterruptable power supply. Although first-order prediction control method shows a good characteristics to rectifier load, it is not sufficient to reduce steady state errors generated in nonlinear loads such as rectifier loads and phase controled loads. So we also employed a repetitive control method. A repetitive control method can eliminate steady state errors in the distorted output voltage caused by cyclic loads. The presented control scheme is verified through simulation and experiment. Experimental results Implemented on a single phase PWM inverter equipped with a LC output filter with 3 kVA, 60 Hz are shown.

Parallel Operation of Three-Phase Four wire UPS using Droop Control (Droop Control을 이용한 3상 4선식 UPS의 병렬운전)

  • Kim, Hyunseob;Han, Jungho;Song, Joong-Ho
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.27 no.4
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    • pp.88-95
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    • 2013
  • A new droop control method which can be applied to 3-phase 4-wire uninterruptible power supply is proposed in this paper. The droop control method for parallel operation is very attractive one as UPS parallel operation can be carried out without any data communication devices provided among UPS systems connected, but it reportedly shows a PnP(plug-and-play) problem. A basic reason why a circulating current could flow among parallel-connected UPS systems is clearly investigated as well when droop-controlled-ups systems are operated in the manner of PnP. The proposed algorithm is deduced from the investigated result and is basically structured to keep a balanced frequency and balanced voltage profile against power variation. This paper shows that balanced parallel operation of droop control method can be obtained under unbalanced load as well as balanced load conditions when PnP operation is needed and load change occurs.

Line-Interactive UPS for Low-Voltage Microgrids

  • Zhang, Ping;Cai, Huanyu;Zhao, Hengyang;Shi, Jianjiang;He, Xiangning
    • Journal of Power Electronics
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    • v.15 no.6
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    • pp.1628-1639
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    • 2015
  • Line-interactive uninterruptible power supply (UPS) systems are good candidates for providing energy storage within a microgrid. In this paper, a control scheme for a line-interactive UPS system applied in a low-voltage microgrid is presented. It is based on the Q-w and P-E droop control to achieve a seamless transition between grid-connected and stand-alone operation modes. Moreover, a new model for designing the controllers is built in the dq-frame based on the instantaneous power definition. The new-built model takes into account the dynamic performance of the output impedance of the inverter in the dq-frame and can be evaluated in the time domain. Compared to the traditional model based on the instantaneous power definition, the new-built model is more accurate to describe the dynamic performance of the system. Simulation and experimental results obtained with a microgrid consisting of two 40-kW line-interactive UPS systems are given to validate the control strategy of the line-active UPS system and the accuracy of the new-built model.

A development of Diagnosis Monitoring System for UPS DC Link Capacitors using Zigbee Wireless Communication (Zigbee 무선통신을 이용한 UPS DC링크 커패시터의 고장 모니터링 시스템 개발)

  • Kim, Dong-Jun;Shon, Jin-Geun;Jeon, Hee-Jong
    • The Transactions of the Korean Institute of Electrical Engineers P
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    • v.61 no.1
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    • pp.41-46
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    • 2012
  • Electrolytic power capacitors have been widely used in power conversion system such as inverter or UPS because of characteristics of large capacitance, high-voltage and low-cost. The electrolytic capacitor, which is most of the time affected by the aging effect, plays a very important role for the power-electronics system quality and reliability. Therefore it is important to diagnosis monitoring the condition of an electrolytic capacitor in real-time to predict the failure. In this paper, the on-line remote diagnosis monitoring system for UPS DC link electrolytic capacitors using low-cost single-chip zigbee communication modules is developed. To estimate the health status of the capacitor, the equivalent series resistor(ESR) of the component has to be determined. The capacitor ESR is estimated by using RMS computation using BPF modeling of DC link ripple voltage/current. Zigbee-based hardware experimental results show that the proposed remote capacitor diagnosis monitoring system can be applied to UPS successfully.

Improved Switching Frequency in Delta Modulated Inverter for UPS Applications

  • Sodaban, C.;Tipsuwanporn, V.;Thepsatorn, P.;Piyarat, W.;Witheephanich, K.
    • 제어로봇시스템학회:학술대회논문집
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    • 2004.08a
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    • pp.986-989
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    • 2004
  • The concept and results of a simple constant switching frequency delta modulation scheme suitable for DC-AC power conversion in uninterruptable power supply (UPS) applications are presented. Unlike the traditional delta modulation scheme, the scheme has a well defined harmonic spectrum, resulting in a simple filter design and reduced radio interference.

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