• Title/Summary/Keyword: Power quality

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Power Quality Monitoring System of Using Power Line Communication (전력선통신을 이용한 전력품질 모니터링 시스템)

  • Hong Ducpyo;Choi Jaeho
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.19 no.4
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    • pp.91-97
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    • 2005
  • As the developing of industry, the nonlinear equipments as inverter, converter, SMPS(Switching Mode Power Supply) and motor have been increased. But the sensitive electronic loads to the power quality, such as computers and other electronic equipments, have been spreaded out very fast. Thus, the power quality(PQ) problems and the real time power quality monitering(PQM) are one of the important issues in industry and building area for the intelligent control of the systems. One of them, PQM using PLC(Power Line Communication) have good merits that can send and receive the PQ information without any new network line. This paper presents the PQM hardware and software to monitor the PQ information by using PLC that meets the categories of IEEE Std. 1159.

Effect of Harmonics and High-Frequency on OLEV System in Distribution Power System (온라인 전기자동차 시스템의 고조파 및 고주파가 배전계통에 미치는 영향에 관한 연구)

  • Choi, Seong-Ho;Huh, Jae-Sun;Han, Woon-Ki;Kim, Jae-Chul
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.63 no.6
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    • pp.738-745
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    • 2014
  • Recently, various measures have been discussed for overcoming depletion of fossil fuels and environmental pollution. One of the measures is electric vehicles. But electric vehicles has some limitations from high cost of battery and low efficiency, so operation distance of electric cars is limited. Also there are difficulties that charging lines should be connected by an electric car whenever it charges. Thus, many studies have been conducted to overcome the limitation using conventional batteries of electric vehicles. As a result, the OLEV(On-Line Electric Vehicle) was developed. But the OLEV system is some limitations. The OLEV system causes power quality problems when it charges. Power quality problem cannot be ignored because OLEV systems are closely connected by distribution grids. In this paper, the OLEV system is designed by using PSCAD/EMTDC, and the power quality is measured and evaluated. Power quality is divided by two cases; harmonics and high-frequency. Harmonics were evaluated according to IEEE Std. 519-1992. But the evaluation of High-frequency could not take it because there was no standard. For this reason, the data measured by OLEV system was compared with the EN50065 regulation.

Development of a Data Acquisition System for the Testing and Verification of Electrical Power Quality Meters

  • Simic, Milan;Denic, Dragan;Zivanovic, Dragan;Taskovski, Dimitar;Dimcev, Vladimir
    • Journal of Power Electronics
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    • v.12 no.5
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    • pp.813-820
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    • 2012
  • This paper presents the development of a software supported acquisition system for metrological verification and testing of the equipment for monitoring and analysis of the basic electrical power quality parameters. The described procedure consists of two functionally connected segments. The first segment involves generation of the reference three-phase voltage signals, including the possibility of simulation of the various power quality disturbances, typical for electrical power distribution networks. The second part of this procedure includes the real-time recording of power quality disturbances in three-phase distribution networks. The procedure is functionally supported by the virtual instrumentation concept, including a software application developed in LabVIEW environment and data acquisition boards NI 6713 and NI 9215A. The software support of this system performs graphical presentation of the previously generated and recorded signal waveforms. A number of the control functions and buttons, implemented on the virtual instrument front panels, are provided to adjust the basic signal acquisition, generation and recording parameters.

Noisy Power Quality Recognition System using Wavelet based Denoising and Neural Networks (웨이블릿 기반 잡음제거와 신경회로망을 이용한 잡음 전력 품질 인식 시스템)

  • Chong, Won-Yong
    • Journal of the Institute of Convergence Signal Processing
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    • v.13 no.2
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    • pp.91-98
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    • 2012
  • Power Quality (PQ) signal such as sag, swell, harmonics, and impulsive transients are the major issues in the operations of the power electronics based devices and microprocessor based equipments. The effectiveness of wavelet based denoising techniques and recognizing different power quality events with noise has been presented in this paper. The algorithms involved in the noisy PQ recognition system are the wavelet based denoising and the back propagation neural networks. Also, in order to verify the real-time performances of the noisy PQ recognition systems under the noisy environments, SIL(Software In the Loop) and PIL(Processor In the Loop) were carried out, resulting in the excellent recognition performances.

An Analysis of the Relationship between Elevator Emergency(Entrapment) and Situation Measurement of Sag/Interruptions at the Switchboard

  • Kim, Gi-Hyun;Lim, Young-Bae;Bai, Seok-Myung;Kim, Jae-Chul;Lee, Hee-Tae
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.21 no.4
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    • pp.36-44
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    • 2007
  • This study researched the mutual relationship between elevator emergencies(sudden stops, entrapment) and power quality such as voltage interruptions or sags. To analyze the power quality at the elevator switchboard of an apartment, the on-line power quality(sag, swell, and interruption, etc.) were measured and error messages(under voltage error, etc.) in the elevator control room were researched. Also the performance and susceptibility for stops were evaluated and stated through the testing of three pieces of simulated test equipment with an EN12016(2004) standard setting and the magnitude and duration data of the measured sag or interruption. This paper will use these data in the analysis of the mutual relationship between power quality and elevator emergencies.

Connected Characteristics for Small Generation Source of Low Voltage Model Grids (저압 모의선로에 소형발전원 연계시 특성)

  • Lee, Sang-Woo;Kang, Jin-Kyu;Lee, Dong-Ha;Park, Tae-Joon
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.27 no.2
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    • pp.45-53
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    • 2013
  • In this paper, we analyze the typical phase voltage and line current waveform characteristics of the distribution system with 3 phase small synchronous generation source in case with load and non-load group, in order to investigate the power quality for end load connected of generation source. As demonstrated by our experimental results, the distortion and power quality of phase voltage and line current waveform were relatively good for low voltage 3 phase model grids connected of 3 phase small synchronous generation source in case with non-load group. However, distortion and power quality of voltage and current waveform was poor for low voltage 3 phase model grids connected to 3 phase small synchronous generation source in the load group with some phase voltage and frequency difference. From the above results, we conclude that the phase voltage and frequency of 3 phase generation source must be identical to that of distribution system source to maximize the power quality. Also, special attention is required in case of having load group or non-load group to 3 phase generation source.

Analysis of Anti-Islanding Schemes using Frequency Drift in Distributed Generation System (분산전원 시스템의 주파수 변동을 통한 단독운전 방지기법 분석)

  • Jo, Yeong-Min;Cho, Sang-Yoon;Song, Seung-Ho;Choy, Ick;Choi, Ju-Yeop;Lee, Young-Kwoun
    • The Transactions of the Korean Institute of Power Electronics
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    • v.20 no.3
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    • pp.247-254
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    • 2015
  • Unintentional islanding results in safety hazards, power quality degradation, and many other issues. Thus, islanding detection of grid-connected distributed generation system is a key function for standards compliance. Many anti-islanding schemes are currently being studied; however, existing anti-islanding schemes used in inverters have power quality degradation and non-detection zone issues. Therefore, this paper analyzes existing anti-islanding schemes by using frequency drift in accordance with both islanding detection performance and power quality. This paper also proposes a new anti-islanding scheme by using frequency drift. Both simulation and experimental results show that the proposed scheme has negligible power quality degradation and no non-detection zones compared with other existing schemes.

The Design of Control Algorithm for Unified Power Quality Compensator (3상 직병렬보상형 전력품질 보상장치(UPQC)의 제어 알고리즘 설계)

  • Jeon Jin Hong;Kim Tae Jin;Ryoo Hong Je;Kim Hwang Su
    • Proceedings of the KIEE Conference
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    • summer
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    • pp.351-353
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    • 2004
  • In recent years, customers and power supplies are interested in power quality. Demands of customers are change from standard quality of distribution power system to various high quality of distribution power system. so, it is necessary to apply power quality compensator. in our project, we develop the UPQC(Unfied Power Quality Compensator of 45kVA which compensates power factor and voltage sag, interruption. it is very frequently occurred power quality $problems^{[1-3]}$ As a series and shunt compensator, UPQC consists of two inverters with common do link capacitor bank. It compensates the current quality in the shunt part and the voltage quality in the series part. In this paper, we present the design and control algorithm for 4SkVA UPQC system. As a control algorithm is implemented by digital controller, we consider sample-and-hold of signals. In this simulation, we use EMTDC/PSCAD V3.0 software which can simulate instantaneous voltage and current.

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Energy Yield, Power Quality and Grid Integration of Wind Energy Converters

  • Hanitsch R. E.
    • KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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    • v.5B no.2
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    • pp.97-102
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    • 2005
  • Because of the limited fossil resources and the need to avoid emissions and toxic waste the future energy supply will be based on a large portion of renewable energies: wind-, solar-, biomass- and geothermal energy. Focus is on the utilization of wind energy coming from onshore- and offshore-sites. Generating electricity from wind is state of the art and feeding large amounts of wind power into the electrical grid will create some additional problems. Suggestions concerning energy storage will be made and the problem of power quality is discussed.

The study on the power quality measurement using wavelet transform in the grid-connected photovoltaic system (웨이브렛 변환을 이용한 태양광 발전시스템의 power quality 측정에 관한 연구)

  • Kim, Il-Song
    • 한국신재생에너지학회:학술대회논문집
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    • 2010.06a
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    • pp.51.1-51.1
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    • 2010
  • 본 논문에서는 wavelet 변환을 이용하여 태양광 발전 시스템의 계통 전원 고조파를 측정하는 방법을 연구하였다. PCS(Power Conditioning System)는 태양전지의 전력을 교류로 변환하여 계통에 연계시키는 장치이다. 직류에서 교류로 변환할 때 스위칭 노이즈가 발생하고, 전력품질이 약화되게 된다. Wavelet 이론은 시간 파형을 주파수 성분으로 분해할 수 있는 기술이다. 이중에서 MLD(Multi-evel Decomposition)기법은, 계산량이 적으면서도 빠른 시간 내에 고조파 성분들을 알아낼 수 있다. 시스템 모델링과 wavelet 이론 소개, 그리고 컴퓨터 모의실험과 DSP 제어기를 이용한 실험 결과로서 본 연구의 타당성을 입증하였다.

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