• Title/Summary/Keyword: voltage sag/swell

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Sag-Swell Generator for Power Quality Disturbance of Dynamic UPS System (전력품질을 고려한 다이나믹 UPS 시스템의 Sag-Swell 발생기)

  • Ahn J.S.;Choi K.J.;Chun T.W.;Nho E.C;Kim I.D.;Kim H.G.
    • Proceedings of the KIPE Conference
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    • 2003.07a
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    • pp.193-196
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    • 2003
  • This paper describes a new Sag-Swell generator for the test of custom power devices such as UPS, DYR, DSTATCOM, 5575, etc. The proposed science has good features of simple structure, high reliability, wide range of Sag and Swell variation, and easy control. Outage, harmonic distortion, notches, and voltage unbalance also can be generated. The operation principle of the proposed scheme is described and verified through simulations.

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Sag-Swell Generator for the test of 3-phase Dynamic UPS (3상 다이나믹 UPS의 성능 시험을 위한 Sag-Swell 발생기)

  • Kim, J.W.;Lee, K.S.;Byun, W.Y.;Nho, E.C.;Kim, I.D.;Chun, T.W.;Kim, H.G.
    • Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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    • 2004.05a
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    • pp.514-517
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    • 2004
  • This paper describes a new 3 phase Sag-Swell generator for the test of custom power devices such as UPS, DVR, DSTATCOM, SSTS, etc. The proposed scheme has good features of simple structure, high reliability wide range of sag and swell variation, It can also generate voltage outage. The control scheme for the generation is simple. The operation principle of the proposed scheme is described and verified through simulations.

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Implementation of Single-phase Voltage Sag/swell Compensator using Direct Power Conversion (직접전력변환 방식의 단상 sag/swell 보상기 구현)

  • Lee, Sang-Hoey;Cha, Han-Ju
    • Proceedings of the KIEE Conference
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    • 2009.04b
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    • pp.118-120
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    • 2009
  • 본 논문에서는 직접 전력변환방식의 단상 sag/swell 보상기를 구현하였다. 제안된 보상기는 정현파 입력/ 출력 필터, 직렬연결 변압기와 dc 링크 커패시터부가 없는 단상 back-to-back PWM컨버터로 구성되어 있다. 이 보상기의 장점은 dc-link 진해 커패시터가 제거되어 전력회로부가 간단하게 구현되어 향상된 신뢰성 및 내구성을 확인 할 수 있으며 동시에 단상 전압 sag/swell을 보상하며 스위칭 손실을 줄이는 간단한 PWM 방법을 들 수 있다. 더구나, 제안된 방법은 일반적인 직접 전력변환방식에서 요구되어지는 복잡한 4-step 전류 방법이 필요 없는 간단한 전류제어방법을 채용할 수 있는 구조이며 제안된 보상기의 구조와 PWM 방법의 타당성을 프로토타입 하드웨어를 제작하여 실험결과로 보상기의 우수성을 확인하였다.

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Three-Phase Z-Source Dynamic Voltage Restorer with a Fuel Cells Source (연료전지 전원을 갖는 3상 Z-소스 동적 전압 보상기)

  • Jung, Young-Gook
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.22 no.10
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    • pp.41-48
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    • 2008
  • This paper proposes a three-phase Z-source dynamic voltage restorer (Z-DVR) to mitigate the voltage sag for the critical loads. The proposed system is composed of passive filter and Z-source topology inverter. As an ESS(Energy Storage System) of the proposed system is employed the Proton Exchange Membrane Fuel Cells (PEMFC). To calculate and control the harmonics and compensation voltage, $i_{d}-i_{q}$ theory in dq rotating reference frame and PI controller are used. In case that three-phase voltage sags occurred, a PSIM simulation was done for the performance comparison of the conventional method employed battery stacks and proposed method. As a result, considering the voltage compensation performance, each method was nearly similar. Also, the compensation performance and the %THD(%Total Harmonic Distortion) result under the various source voltage conditions (sag or swell) were presented and discussed to show the performance of the proposed system.

Estimation of Voltage Swell Frequency Caused by Asymmetrical Faults

  • Park, Chang-Hyun
    • Journal of Electrical Engineering and Technology
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    • v.12 no.4
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    • pp.1376-1385
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    • 2017
  • This paper proposes a method for estimating the expected frequency of voltage swells caused by asymmetrical faults in a power system. Although voltage swell is less common than voltage sag, repeated swells can have severe destructive impact on sensitive equipment. It is essential to understand system performance related to voltage swells for finding optimal countermeasures. An expected swell frequency at a sensitive load terminal can be estimated based on the concept of an area of vulnerability (AOV) and long-term system fault data. This paper describes an effective method for calculating an AOV to voltage swells. Interval estimation for an expected swell frequency is also presented for effective understanding of system performance. The proposed method provides long-term performance evaluation of the frequency and degree of voltage swell occurrences.

Reactive Current Assignment and Control for DFIG Based Wind Turbines during Grid Voltage Sag and Swell Conditions

  • Xu, Hailiang;Ma, Xiaojun;Sun, Dan
    • Journal of Power Electronics
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    • v.15 no.1
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    • pp.235-245
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    • 2015
  • This paper proposes a reactive current assignment and control strategy for a doubly-fed induction generator (DFIG) based wind-turbine generation system under generic grid voltage sag or swell conditions. The system's active and reactive power constrains during grid faults are investigated with both the grid- and rotor-side convertors (GSC and RSC) maximum ampere limits considered. To meet the latest grid codes, especially the low- and high-voltage ride-through (LVRT and HVRT) requirements, an adaptive reactive current control scheme is investigated. In addition, a torque-oscillation suppression technique is designed to reduce the mechanism stress on turbine systems caused by intensive voltage variations. Simulation and experiment studies demonstrate the feasibility and effectiveness of the proposed control scheme to enhance the fault ride-through (FRT) capability of DFIG-based wind turbines during violent changes in grid voltage.

Z-source power quality conditioner with compensation capability of voltage sag-swell and harmonics (전압sag-swell과 고조파 보상기능을 갖는 Z-소스 전력품질보상시스템)

  • Park, Hee-Jae;Oh, Seung-Yeol;Jung, Young-Gook;Lim, Young-Cheol
    • Proceedings of the KIPE Conference
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    • 2009.11a
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    • pp.290-292
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    • 2009
  • 본 연구에서는 배전계통의 전압 및 전류 품질을 통합적으로 개선할 수 있는 수동필터 연계형 Z-소스 전력품질 보상 시스템을 제안한다. 제안된 시스템의 주안점은 전압의 변동을 보상하는 직렬형 인버터와 고조파를 보상하는 병렬형 인버터에 각각 Z-소스 토폴로지를 적용하는 것이다. 전압 sag와 swell이 발생하는 과도상태에서 제안된 시스템의 성능을 검증하기 위하여 PSIM시뮬레이션을 하여 타당성을 입증하였다.

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Quasi Z-Source Voltage Sag-Swell Compensator by Instantaneous Value Detection Algorithm (순시치 검출 기법을 이용한 Quasi Z-소스 순간전압 Sag-Swell 보상기)

  • Lee, Ki-Taeg;Jung, Young-Gook;Lim, Young-Choel
    • Proceedings of the KIPE Conference
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    • 2009.11a
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    • pp.146-148
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    • 2009
  • 본 논문에서는 새로운 Quasi Z-소스 순간전압 Sag-Swell 보상기를 제안한다. 제안된 시스템은 Quasi Z-소스 교류-교류 컨버터를 기반으로 하며, 입력단과 출력단이 공통 접지이며, 연속적인 입력전류로 동작하는 특징을 가지고 있다. 또한 평균치 제어 기법의 단점을 보완하기 위한 방법으로 실시간 샘플링 검출기법을 이용한 알고리즘을 적용하여 샘플링 구간 동안 평균치 값을 계산해서 순간전압 변동을 검출해 내는 기법을 적용했다.

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Single-Phase Impedance-Source Dynamic Voltage Restorer (단상 임피던스-소스 동적 전압 보상기)

  • Park, H.J.;Jung, Y.G.;Lim, Y.C.
    • Proceedings of the KIPE Conference
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    • 2008.06a
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    • pp.458-461
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    • 2008
  • This paper deals with a single-phase impedance-source dynamic voltage restorer (Impedance-DVR) to mitigate voltage sag/swell for the critical loads. The proposed system is composed of passive filter and impedance-source topology inverter. As an ESS(Energy Storage System) of the proposed system is employed the Proton Exchange Membrane Fuel Cells (PEMFC). To calculate and control the compensation voltage, single-phase $^id-^iq$ theory in dq rotating reference frame and PI controller are used. Simulation results under voltage sag and swell are presented to show the performance.

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Digital-Controlled Single-Phase Unified Power Quality Conditioner for Non-linear and Voltage Sensitive Loads

  • Ryoo Hong-Je;Kim Jong-Soo;Kisck Dragos Ovidiu
    • KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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    • v.5B no.4
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    • pp.374-381
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    • 2005
  • The ability to provide quality power has become a significant issue in power systems. The main causes of poor power quality are harmonic currents, poor power factor, supply-voltage variations, etc. A technique of achieving both active current distortion compensation, power factor correction and also mitigating the supply-voltage variation (sag or swell) at the load side is presented in this paper. The operation and rating issues of the proposed Single-phase Unified Power Quality Conditioner are also highlighted. To reduce the total cost while simultaneously increasing the performance, the system is fully digitally controlled using the fixed-point TMS320F240 digital signal processor. The performances of the UPQC, which is composed by shunt and series PWM controlled-converters, have been verified on a laboratory prototype.