• Title, Summary, Keyword: Power quality

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The Study of Distributed Disturbance Recording System (분산형 사고파형저장 시스템에 대한 연구)

  • Park, Jong-Chan;Lee, Se-In
    • The Transactions of the Korean Institute of Electrical Engineers P
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    • v.57 no.1
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    • pp.30-35
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    • 2008
  • In this paper, the application of power Quality monitoring based on Sampled Value(SV) which is introduced in the IEC61850 International Standard for substation communication are discussed. Firstly, while Merging Unit(MU) is designed as a process level device transmitting sensor data, the practical problems such as time delay compensation and optical fiber communication are encountered. Secondly, the Sampled Value message which is proper to a power quality monitoring system is presented. Because the power quality monitoring system requests less time-critical service compared to protection and control applications, the Sampled Value service message structure is introduced to improve efficiency. Lastly, the power quality monitoring server having various power quality analysis functions is suggested to verify the performance of Merging Unit With the diverse experiments, it is proved that the process bus distributed solution is flexible and economic for the power quality monitoring.

Performance Analysis of UPQC(Unified Power Quality Conditioner) with Compensation Capability for Voltage Interruption (순간정전에 대한 보상능력을 갖는 UPQC(Unified Power Quality Conditioner)의 성능해석)

  • 김희중;배병열;한병문;설승기;조보형
    • The Transactions of the Korean Institute of Electrical Engineers A
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    • v.52 no.5
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    • pp.279-286
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    • 2003
  • A new UPQC(unified power quality conditioner), which consists of series inverter, shunt inverter, dc/dc converter, and energy storage, is proposed. The proposing UPQC can compensate reactive power, harmonics, voltage sag and swell, voltage unbalance, and voltage interruption. The control strategy for the proposing UPWQC was derived using the instantaneous power method. The performance of proposing system was analyzed by means of the EMTDC/PSCAD simulation and the experimental work with the hardware prototype. The proposing UPQC has the ultimate capability of improving power quality at the point of installation on power distribution systems or industrial power systems and can be utilized for the custom power device in the future distribution system.

Performance Analysis for the UPQC(Unified Power Quality Conditioner) Interconnected to the Distributed Generation System (분산전원 연계형 UPQC(Unified Power Quality Conditioner)의 성능해석)

  • 김희중;배병열;한병문
    • The Transactions of the Korean Institute of Electrical Engineers A
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    • v.53 no.3
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    • pp.152-160
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    • 2004
  • A novel UPQC(Unified Power Quality Conditioner), which consists of series inverter, shunt inverter, distributed generation system, is proposed. The proposing system can compensate reactive power, harmonics, voltage sag and swell, voltage interruption etc. through the change of paralleling operation mode and islanding operation mode. The control strategy for the proposing system was derived using the instantaneous power method. The performance of proposing system was analyzed by means of the PSCAD/EMTDC simulation and the experimental work with the hardware prototype. The proposing system has the ultimate capability of improving power quality at the point of installation on power distribution systems or Industrial power systems and can be utilized for the custom power device in th future distribution system.

Power Flow Control of a Multi-bus/Three-feeder Distribution System Using Generalized Unified Power Quality Conditioner

  • Mohammed, B.S.;Ibrahim, R.;Perumal, N.;Rao, K.S. Rama
    • Journal of Electrical Engineering and Technology
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    • v.10 no.1
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    • pp.8-17
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    • 2015
  • This paper analyses the power flow of a three-feeder/multi-bus distribution system by a custom Generalized Power Quality Conditioner (GUPQC). The GUPQC has been realized by three voltage source converters (VSCs) coupled back-to-back through a common DC-link capacitor on the DC-side. One feeder was controlled by the shunt compensator, whereas each of the other two feeders was controlled by the proposed novel series compensator. The GUPQC has the capability to simultaneously compensate voltage and current quality problems of a multi-bus/three-feeder distribution system. Besides that, the power can be transferred from one feeder to other feeders to compensate for poor power quality problems. Extensive simulation studies were carried out by using MATLAB/SIMULINK software to establish the ability of the GUPQC to improve power quality of the distribution systems under distorted supply voltage conditions.

Power Quality Early Warning Based on Anomaly Detection

  • Gu, Wei;Bai, Jingjing;Yuan, Xiaodong;Zhang, Shuai;Wang, Yuankai
    • Journal of Electrical Engineering and Technology
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    • v.9 no.4
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    • pp.1171-1181
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    • 2014
  • Different power quality (PQ) disturbance sources can have major impacts on the power supply grid. This study proposes, for the first time, an early warning approach to identifying PQ problems and providing early warning prompts based on the monitored data of PQ disturbance sources. To establish a steady-state power quality early warning index system, the characteristics of PQ disturbance sources are analyzed and summed up. The higher order statistics anomaly detection (HOSAD) algorithm, based on skewness and kurtosis, and hierarchical power quality early warning flow, were then used to mine limit-exceeding and abnormal data and analyze their severity. Cases studies show that the proposed approach is effective and feasible, and that it is possible to provide timely power quality early warnings for limit-exceeding and abnormal data.

Coordinated Control Strategies with and without Circulating Current in Unified Power Quality

  • Feng, Xing-tian;Zhang, Zhi-hua
    • Journal of Power Electronics
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    • v.15 no.5
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    • pp.1348-1357
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    • 2015
  • Under traditional unified power quality conditioner (UPQC) control, a UPQC series converter (SC) is mainly used to handle grid-side power quality problems while its parallel converter (PC) is mainly used to handle load-side power quality problems. The SC and PC are relatively independent. The SC is usually in standby mode and it only runs when the grid voltage abruptly changes. In this paper, novel UPQC coordinated control strategies are proposed which use the SC to share the reactive power compensation function of the PC especially without grid-side power quality problems. However, in some cases, there will be a circulating current between the SC and the PC, which will probably influence the compensation fashion, the compensation capacity, or the normal work of the UPQC. Through an active power circulation analysis, strategies with and without a circulating current are presented which fuses the reactive power allocation strategy of the SC and the PC, the composite control strategy of the SC and the compensation strategy of the DC storage unit. Both of the strategies effectively solve the SC long term idle problem, limit the influence of the circulating current, optimize all of the UPQC units and reduce the production cost. An analysis, along with simulation andexperimental results, is presented to verify the feasibility and effectiveness of the proposed control strategies.

A Power Quality Monitoring System(PQMS) : A Standard of User-Friendly-GUI & Analysis Graphic Representation (전력품질 모니터링 시스템 : User-Friendly-GUI 및 분석 그래프 표준)

  • Kim, Young-Il;Han, Jin-Hee;Yoon, Tai-Wook
    • Proceedings of the KIEE Conference
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    • pp.127-130
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    • 2002
  • Recently, with the increasing use of power semiconductors and microprocessors which are very sensitive to little change of power quality and for coping positively with anticipating power quality disputes between power providers and consumers which are possible to occur by of power market being formed, the power quality problem has gained preponderance among the contemporary research areas. To serve these purposes, the integrated system has been researched and developed for power quality analysis and monitoring, which provides speedy and powerful functions by the growth of computer hardware and information technology. But the advent of fast and lower price hardware make little difference in an application on many systems. As a result, the key issues of constructing power quality monitoring system are in the management of data obtained, accurate algorithms, graphic representation and user-friendly-environment for easy and clear analysis results. So, in this paper it will be introduced that the standard of user-friendly-GUI(Graphic User Interface) and analysis graphic representation for intuitive understanding of results from power quality analysis based on consideration of several systems currently being in use.

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The Development of Integrated Power Quality Diagnosis System for Power System (전력계통 전력품질 통합진단시스템 개발)

  • Kwak, N.H.;Jeon, Y.S.;Park, S.H.;Lee, I.M.;Park, H.C.
    • Proceedings of the KIEE Conference
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    • pp.277-279
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    • 2005
  • Recently, due to the increase of power conversion devices and nonlinear loads with the development of information, communication and control technologies, the instantaneous minute interruption factors such as voltage & current harmonics, surge occurring frequency, instantaneous voltage variation, voltage unbalance, flicker etc. have greatly threatened the power quality, and the deterioration of electric power facilities and the functional error of controllers are increasing. As such an instantaneous minute interruption appears to be small and local, accurate evaluation with measurement is difficult and total analysis system is required through a wide range of power quality effect analysis such as the simultaneous measurement on various power supply phenomena and the analysis on the interrelation with system loads. Most of conventional power quality diagnosis equipments have beer developed and applied, which were able to measure the stability rate of frequency, the stability rate of voltage, the electricity-failure duration etc, However, they were insufficient to analyze the system present situation, understand the cause of the failure occurred by the problem of power quality and analyze out the phenomena. Accordingly, this study will address the development of the system for a wide range of power quality diagnosis over the present level, the system for supporting the determination such as the analysis on risk factors, failure mode and impact, the system for harmonic evaluation based on international standards(IEC 61000 Series) and the total power quality diagnosis network & system with the extension and openness as a local and national-scale broadband power quality diagnosis system.

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Definition of Powers and Power Quality Factors at a Point of Common Coupling in Single-Phase Systems and Three-Phase Systems

  • Kim, Hyosung;Frede Blaabjerg;Jensen, Birgitte-Bak
    • Journal of Power Electronics
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    • v.2 no.1
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    • pp.32-45
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    • 2002
  • This paper proposes an unified definition of powers for various circuit conditions such as balanced/unbalanced, sinusoidal/non-sinusoidal, and linear/nonlinear, fur single-phase systems and three-phase systems. Conventional reactive power is more classified into an interactive power and an alternating power. These powers are defined both in the time domain and the frequency domain consistently, and agree well with the conservation law. Several important power quality factors are defined to measure and evaluate the power quality fur the various circuits in the single-phase and three-phase systems. Simulation results show the power quality factors can evaluate and classify the various circuit conditions clearly.

Study of Power Quality Measurement U57 Windturbine (U57 풍력발전기 전력품질 실증연구)

  • Lee, Byung-Chul;Park, Hee-Chul;Hwang, Jin-Su;Ryu, Ji-June
    • 한국신재생에너지학회:학술대회논문집
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    • pp.310-314
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    • 2008
  • The exploitation of the wind energy resource is a rapidly growing area world-wide. The number of installed units is continuously increasing, and it is important to respect and to deal with the impact of wind turbine. This paper addresses the power quality characteristics of U57 Wind Turbine. 750kW gearless type wind turbine for low wind speed, named U57, is developed by UNISON. The power quality measurement system consists of measuring WTG output current, line-to line voltage and wind speed signal. With using measured data, power quality measurement is evaluated about maximum power, reactive power, voltage fluctuation, harmonics according to IEC 61400-21.

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