• Title, Summary, Keyword: Power quality

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A Study on the Single Phase Voltage-Controlled Active Power Filter for Power Quality Improvement (전력품질 개선을 위한 단상 전압제어형 능동전력필터 시스템에 관한 연구)

  • 손진근
    • The Transactions of the Korean Institute of Electrical Engineers B
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    • v.52 no.5
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    • pp.238-245
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    • 2003
  • In this paper, a single Phase voltage source voltage-controlled active power filter(APF) for power quality improvement was proposed. The proposed APF has the performance of harmonic suppression and unity power factor correction. The performance of harmonic suppression can be obtained by controlling the waveshape of the APF output voltage to be sine wave. And, unity power factor is controlled by the reactive power control loop of the APF output. Simulation and experimental results using diode rectifier showed that the voltage-controlled APF, unlike the current-controlled APF, can reduce the voltage harmonics as well as current harmonics. Also the results showed that the input dover factor and power quality were greatly improved.

Study on the measuring system of power quality for transmission system (송전계통의 전기품질 측정 시스템에 관한 연구)

  • Kim, Yeoung-Noh;Shin, Bong-Il;Lee, Hee-Chul;Kwak, No-Hong;Jeon, Young-Soo;Park, Sang-Ho;Lee, Il-Moo
    • Proceedings of the KIEE Conference
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    • pp.107-109
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    • 2006
  • The additional matters appear to be considered in several aspects for building up power-quality measuring system of transmission system(high voltage system) compared to distribution system(middle or low voltage system). Like in distribution system, input signals are also received from PT and CT source of voltage and current respectively in transmission system and applied in accordance with a certain rate. In this case, very big error rate can be occurred according to the specification of the measuring system as the applying rate is bigger than in distribution system beyond comparison. In addition, when the abnormal signal occurred such as sag/swell, interruption, transient etc., power quality of other sites linked to the system also should be checked to find the accurate cause of the abnormal power-quality signals from the corresponding site. Accordingly, the accurate diagnosis on the condition of Power quality for the system depends on the way how the synchronization system is brought along for each site. This paper will suggest the solution for the most effective system building focused on how to solve the problem of the error rate and synchronization described in the above when building up the measuring system of power quality for transmission system.

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Development of Power Quality Monitoring System (전력품질 감시 시스템 개발(3) : 전력품질 감시 시스템)

  • Bahng, Soon-Jeong;Kim, Young-Il;Han, Jin-Hee;Yoon, Tai-Wook
    • Proceedings of the KIEE Conference
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    • pp.158-160
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    • 2003
  • 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, this paper is described the integrated system for power quality monitoring, which provides speedy and powerful functions by analyzing the Event data and diverse graphic interfaces for user.

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Power Quality Analysis of Wind Farms interconnected in Jeju System during HVDC Overhaul (HVDC Overhaul 기간 중 제주계통에 연계된 풍력발전의 전력품질 분석)

  • Chae, Woo-Kyu;Yoon, Gi-Gab;Cho, Seong-Soo;Jung, Won-Wook
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.57 no.11
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    • pp.1946-1953
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    • 2008
  • Power system of Jeju is interconnected to the mainland using HVDC and that is also interconnected to three wind farms. It will be difficult to control of Jeju power system if HVDC is disconnected or HVDC is overhauled under large scale wind farms interconnected. We measured and analysed the power quality of two substation and two wind farms to assess that wind farms have an effect on Jeju system during the HVDC overhaul last May. We concentrated on the power quality like frequency, voltage variation, voltage harmonics, current harmonics, flicker. We can found that the frequency of Jeju system is very unstable during overhaul, so the frequency of Jeju system can be variated easily by wind farm's rapid output power variation. There are some benefits and weak points in power quality between two wind farms because each wind farm is consist of different wind turbines.

Power Quality Monitoring System with a New Distributed Monitoring Structure

  • Won, Dong-Jun;Chung, Il-Yop;Kim, Joong-Moon;Ahn, Seon-Ju;Moon, Seung-Il;Seo, Jang-Cheol;Choe, Jong-Woong
    • KIEE International Transactions on Power Engineering
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    • v.4A no.4
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    • pp.214-220
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    • 2004
  • Power quality monitoring is the cornerstone for power quality analysis, diagnosis and improvement. The measurement of power quality (PQ) evolves from instantaneous metering to continuous monitoring. Furthermore, recent technologies enable us to construct more flexible, reliable, rapid and economical power quality monitoring system (PQMS). Therefore, this paper presents an improved PQMS with a new distributed monitoring structure. The proposed PQMS consists of a PQ meter, PQ analyzer and GUI. The PQ meter only collects raw data and the PQ analyzer performs power quality analysis. It has several advantages compared to conventional structures in economic efficiency, modularity, speed, etc. PQ monitoring algorithms to catch steady-state trends and to detect PQ events are also adapted to the proposed structure. Using the proposed structure and monitoring algorithm, a prototype PQMS is constructed and real-time testing is performed.

The power quality analysis of interconnection with the dispered Micro Gas Turbine (분산형 Micro Gas Turbine 계통연계 전력품질 분석)

  • Yoon, Gi-Gab;Hur, Kwang-Beom;Rhim, Sang-Kyu;Kim, Sang-Joon;Cho, Hyung-Rae
    • Proceedings of the KIEE Conference
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    • pp.547-548
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    • 2006
  • This paper deals with the power quality of Micro Gas Turbine(MGT) generation system which is connected with distribution system. Measurements to evaluate the power quality of MGT generation system are performed with parameters that are frequency, voltage change, harmonics and flicker and then Parameters are evaluated.

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Analysis of Power Quality for Extra-High Voltage Customers by Field Tests (실측에 의한 특고압수용가의 전력품질 분석)

  • Ji, Pyeong-Shik;Moon, Jong-Fil
    • The Transactions of the Korean Institute of Electrical Engineers P
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    • v.61 no.2
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    • pp.82-86
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    • 2012
  • Recently, due to the expansion of electric power demands, nonlinear load such as converters and inverters connected to the electric power distribution system, and extensive application of harmonic generation sources with power electric devices, disturbance of the electric power system and its influences on industries have been continuously increasing. In this research, power quality was analyzed for 11 extra-high voltage customers by considering voltage unbalance condition, power factor, THD and TDD. This research will be utilized as fundamental data to improve power quality for power utility.

Development of New Monitoring System for Power Quality Management (새로운 전기품질 감시장치 개발 및 전기품질 관리방안)

  • Nam, Kee-Young;Choi, Sang-Bong;Ryoo, Hee-Suk;Lee, Jae-Duck;Jeong, Seong-Hwan;Kim, Dae-Kyung
    • Proceedings of the KIEE Conference
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    • pp.447-449
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    • 2005
  • Power supply system & environment have been changed according to the universal global electrification, the pursuit of improving productivity and the convenience of life. The various kinds of modem electric facilities and almost of all kinds of digital devices embedded microprocessor are very sensitive to the supplied power quality variations. So, they are stopped and result in large economic damage when even the deterioration of power quality with short duration is occurred, which was not so fatal to the conventional industrial facilities and devices. Conversely, those facilities and digital devices generate many kinds of power quality problems such as harmonic.;, flicker, voltage drop, etc. This paper presents the status of power quality and outlines the development of a new power quality monitoring system based on the experience of a series of authors' researches and field measurements for industrial customers in Korea. It also proposes the functions of the monitoring device and the efficient analysis method based on the Korean electrical act and international standards on power quality. Finally, the authors suggest some countermeasures for advancing the power quality to cope with the competitive electric power market and customers' needs after domestic restructuring of electric power industry.

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A Basic Study on the Development of the Single-Phase Unified Poorer Quality Conditioner (단상용 통합형 전력품질 개선장치의 개발에 관한 기초연구)

  • 노대석;이현옥;오성철;최재석;차준민;김재언
    • The Transactions of the Korean Institute of Electrical Engineers A
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    • v.52 no.2
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    • pp.90-98
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    • 2003
  • Recently, the increasing application of electronic equipments and information devices has heightened the interest in power qualify. The term power quality is applied to a wide range of electromagnetic phenomena on the power system and is also concentrated by all areas such as utilities, their customers and suppliers of load equipments. In engineering terms, power Qualify is expressed by voltage qualify because the power supply system can only control the quality of the voltage. Therefore, the standards in power quality area are devoted to keep the supply voltage within allowable limits. This paper deals with single-phase unified power quality conditioner (UPQC), which ai s at the integration of series-active and shunt-active filter. The series filter il used to compensate for the voltage distortions and the shunt filter is used to provide reactive power and counteract the harmonic current injected by the load. Also, the voltage of the DC link capacitor is controlled to a desired value by the shunt active filter. The validity of the proposed UPQC is demonstrated using both the MATLAB/SIMULINK simulation and the experimental device with DSP (TMS320C32).

Power Quality Disturbance Detection in Distribution Systems Using Wavelet Transform (웨이브렛 변환을 이용한 배전계통의 전력품질 외란 검출에 관한 연구)

  • Son Yeong-Rak;Lee Hwa-Seok;Mun Kyeong-Jun;Park June Ho;Yoon Jae-Young;Kim Jong-Yul;Kim Seul-Ki
    • The Transactions of the Korean Institute of Electrical Engineers A
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    • v.54 no.7
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    • pp.328-336
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    • 2005
  • Power quality has become concern both utilities and their customers with wide spread use of electronic and power electronic equipment. The poor quality of electric power causes malfunctions, instabilities and shorter lifetime of the load. In power system operation, power system disturbances such as faults, overvoltage, capacitor switching transients, harmonic distortion and impulses affects power quality. For diagnosing power quality problem, the causes of the disturbances should be understood before appropriate actions can be taken. In this paper we present a new approach to detect, localize, and investigate the feasibility of classifying various types of power quality disturbances. This paper deals with the use of a multi-resolution analysis by a discrete wavelet transform to detect power system disturbances such as interruption, sag, swell, transients, etc. We also proposed do-noising and threshold technique to detect power system disturbances in a noisy environment. To find the better mother wavelet for detecting disturbances, we compared the performance of the disturbance detection with the several mother wavelets such as Daubechies, Symlets, Coiflets and Biorthogonals wavelets. In our analysis, we adopt db4 wavelet as mother wavelet because it shows better results for detecting several disturbances than other mother wavelets. To show the effectiveness of the proposed method, a various case studies are simulated for the example system which is constructed by using PSCAD/EMTDC. From the simulation results. proposed method detects time Points of the start and end time of the disturbances.