• Title/Summary/Keyword: 3-phase 4-wire system

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Control of 3 - Phase 4 - Wire Isolated Grids

  • Buttner Jurgen;Ellinger Thomas;Muller Andre;Petzoldt Jurgen
    • Proceedings of the KIPE Conference
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    • 2001.10a
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    • pp.816-821
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    • 2001
  • The generation of isolated grids by pulsed converters with characteristics close to the mains of the utility companies is a pretentious task. For generation of three-phase four-wire isolated grids are presented possible topologies and the demands on the system control are processed. For control of all conceivable load and error conditions, an extensive control technology is necessary. This must permit unsymmetrical operating conditions for an unlimited period but recognize errors simultaneously and therefore an overloading the consumer and the power semiconductors reliable may prevent. Measurement results on an experimental plant show the problems to be solved.

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Neutral line current elimination method for Active power filter of three phase four-wire power system (중성선 전류 제거를 위한 3상 4선식 능동 전력 필터)

  • Min, Joon-Ki;Kim, Hyo-Sung;Choi, Jae-Ho
    • Proceedings of the KIEE Conference
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    • 2005.07b
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    • pp.1489-1491
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    • 2005
  • This paper proposes a design method using PQR instantaneous power theory on the active power filter, unbalanced nonlinear load condition and unbalanced source voltage condition in three-phase four-wire systems. For reduction of current harmonics and neutral current, the control structure including repetitive controller is proposed and controller gain is designed. For fully-digital implementation, ramp comparison PWM method was adopted. Simulation results verify good performance of the proposed current control strategy on the shunt APFs.

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Comparison of VUF using Resistor & Inductive Load (저항성 및 유도성 부하의 운전시 전압불평형율의 비교)

  • Kim, Jong-Gyeum;Park, Young-Jeen;Lee, Eun-Woong;Lee, Jong-Han;Lee, Dong-Ju
    • Proceedings of the KIEE Conference
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    • 2005.07b
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    • pp.1062-1064
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    • 2005
  • 3 phase 4-wire system has been widely used in the customer's application due to merit of 1 bank construction of loads such as 1-phase lighting, heat and 3-phase motor. But if the load distribution is not uniformed by the operation conditions, voltage unbalance is highly appeared by the difference of each phase current value. Especially, if the linear load such as resistance or inductive load has different power factor value, voltage unbalance factor is not the same due to the phase angle and magnitude of each phase voltage. In this paper, we composed the measurement device and analyzed by varying of load pattern.

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Design of the Robust Hybrid Controller for Three-Phase Four-Leg Voltage Source Inverter under the Unbalance Load (불평형 부하에서 강인한 3상4족 전압형 인버터를 위한 하이브리드 제어기의 설계)

  • Doan, Van-Tuan;Choi, Woojin
    • Proceedings of the KIPE Conference
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    • 2014.07a
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    • pp.291-292
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    • 2014
  • The three-phase four-leg voltage source inverter (VSI) topology can be an interesting option for the three phase-four wire system. With an additional leg, this topology can achieve superior performance with unbalanced and/or nonlinear load. This paper proposes a new hybrid controller which combines PI controller and resonant controller in synchronous frame for three phase four leg inverter. The hybrid controller is simple in structure and easy to implement. The performance of proposed controller is verified by the experiments and compared with that of the conventional PI controller.

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Neutral Line Current Analysis of Three-phase Four-wire Power System (3상 4선식 전력 시스템의 중성선 전류 분석)

  • Min Joon-Ki;Kim Hyng-Chul;Kim Su-Chel;Choi Jae-Ho
    • Proceedings of the KIPE Conference
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    • 2006.06a
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    • pp.492-494
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    • 2006
  • Neutral line current is analyzed by the neutral line CF in nonlinear load balanced and unbalanced conditions. The worst nonlinear load condition is nonlinear balanced load condition, and It is below CFNL=1.194 that a neutral line current could not excess the rated value

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Interlinking converter considering 1-phase short circuit state of AC-DC microgrid system (AC-DC 마이크로그리드의 각상 1선지락 상태를 고려한 인터링킹 컨버터)

  • Kim, Mi-Na;Choi, Bong-Yeon;Kang, Kyung-Min;Lee, Hoon;An, Chang-Gyun;Won, Chung-Yeun
    • Proceedings of the KIPE Conference
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    • 2019.11a
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    • pp.148-149
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    • 2019
  • Voltage unbalance can be occured in AC-DC microgrid systems when AC loads or AC systems are connected. To solve this problem, 3-phase 4-wire interlinking converter is used. This paper proposes in PLL method that can detect accurate phase and voltage magnitude.

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Loss Comparison and Analysis of 3-phase 4-wire Grid-connected Bi-directional Inverter for Energy Storage System (에너지 저장 장치용 3상 4선식 계통연계 양방향 인버터 구성 방법에 따른 비교 및 분석)

  • Lee, WonJun;Park, Jae Kwang;Ahn, Hyo Min;Lee, Byoung Kuk
    • Proceedings of the KIPE Conference
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    • 2017.11a
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    • pp.127-128
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    • 2017
  • 본 논문에서는 에너지 저장 장치용 3상 4선식 계통 연계 양방향 인버터의 구성 방법에 따른 특성을 비교 분석 한다. 3상-4선식 인버터의 N상을 DC 링크 중성점 결선, 추가적인 전력 반도체 스위치를 이용하여 결선하는 방법, 그리고 변압기를 이용한 결선 방법에 따른 특성을 비교 및 분석을 한다.

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Fabrication of Tungsten Probe Tips for AFM using Electrochemical Etching (전기화학적 에칭법을 이용한 AFM용 텅스텐 탐침 제작에 관한 연구)

  • Han, Gue-Bum;Jang, Hyuna;Ahn, Hyo-Sok
    • Tribology and Lubricants
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    • v.29 no.4
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    • pp.213-217
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    • 2013
  • As commercial atomic force microscopy (AFM) probes made of Si and $Si_3N_4$ have low stiffness, it is difficult to induce sufficient elastic deformation on the surface of a specimen in a tapping mode. Therefore, high-guality phase contrast images can not obtained. On the other hand, a tungsten AFM probe has relatively higher stiffness than a commercial AFM probe. Accordingly, it is expected to provide an enhanced phase contrast image, which is an effective tool for achieving a better understanding of the micromechanical properties of worn surfaces and wear mechanisms. In this study, on electrochemical etching method was optimized to fabricate tungsten probe tips for an AFM. Electrochemical etching was performed by applying pulse waves with a 20% duty cycle at various voltages instead of only a DC voltage, which has been commonly used.

Effective Control of Stiffness of Tungsten Probe for AFM by Electrochemical Etching (전기화학적 에칭에 의한 AFM용 텅스텐 탐침의 강성 제어)

  • Han, Guebum;Lee, Seungje;Ahn, Hyo-Sok
    • Tribology and Lubricants
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    • v.30 no.4
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    • pp.218-223
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    • 2014
  • This paper presents a method of controlling the stiffness of a tungsten probe for an atomic force microscope (AFM) in order to provide high-quality phase contrast images in accordance with sample characteristics. While inducing sufficient deformation on sample surfaces with commercial Si or $Si_3N_4$ probes is difficult because of their low stiffness, a tungsten probe fabricated by electrochemical etching with appropriately high stiffness can generate relatively large elastic deformation without damaging sample surfaces. The fabrication of the tungsten probe involves two separate procedures. The first procedure involves immersing a tungsten wire with both ends bent parallel to the surface of an electrolyte and controlling the stiffness of the tungsten cantilever by decreasing its diameter using electrochemical etching in the direction of the central axis. The second procedure involves immersing the end of the etched tungsten cantilever in the direction perpendicular to the surface of the electrolyte and fabricating a tungsten tip with a tip radius of 20-50 nm via the necking phenomenon. The latter etching process applies pulse waves every 0.25 seconds to the manufactured tip to improve its yield. Finite element analysis (FEA) of the stiffness of the tungsten probe as a function of its diameter showed that the stiffness of the tungsten probes greatly varies from 56 N/m to 3501 N/m according to the cantilever diameters from $30{\mu}m$ to $100{\mu}m$, respectively. Thus, the proposed etching method is effective for producing a tungsten probe having specific stiffness for optimal use with an AFM and certain samples.

The Compensating Unbalanced Source Voltages for Unified Active Power Filter System (직.병렬 능동 전력필터 시스템을 이용한 불평형 전원전압 보상)

  • Kim, Young-Seok;Kang, Min-Hyung
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.56 no.4
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    • pp.716-723
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    • 2007
  • This paper suggests of a 3-phase 3-wire unified active power filter. The system is composed of a series active power filter and a parallel active power filter. The proposed series active power filter compensating unbalance source voltage and current harmonics of the parallel active power filter improves power factor. The proposed algorithm which improves for power factor and harmonic reduction are calculated by the performance function, and which compensates for the unbalanced source voltage is calculated based on the symmetrical component analysis. We composed a combined system of the series active power filter and parallel active power filter to confirm a validity of the proposed control methods. The effectiveness of the proposed algorithm is confirmed by the experiments.