• Title, Summary, Keyword: Point of common coupling

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A New Assessment for the Total Harmonic Contributions at the Point of Common Coupling

  • Han, Jong-Hoon;Lee, Kyebyung;Song, Chong Suk;Jang, Gilsoo;Byeon, Gilsung;Park, Chang-Hyun
    • Journal of Electrical Engineering and Technology
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    • v.9 no.1
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    • pp.6-14
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    • 2014
  • A new method to determine the total harmonic contributions of several customers and the utility at the point of common coupling is presented. The proposed method can quantify the individual harmonic impact of each suspicious harmonic source at the point of common coupling. The individual harmonic impact index is then used to assess the total harmonic contribution of each harmonic source. This index can be calculated by the results processed from instantaneous harmonic voltage and current phasor values. The results demonstrate the performance of the proposed method in terms of steady-state accuracy and response to time-varying operating conditions. The proposed index can be used for billing purposes to control harmonic distortion levels in power systems.

Compensation of Unbalanced PCC Voltage in Off-shore Wind Farms of PMSG Type Turbine

  • Kang, Jayoon;Han, Daesu;Suh, Yongsug;Jung, Byoungchang;Kim, Jeongjoong;Park, Jonghyung;Choi, Youngjoon
    • Proceedings of the KIPE Conference
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    • pp.215-216
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    • 2014
  • This paper proposes a control algorithm for permanent magnet synchronous generator with a back-to-back three-level neutral-point clamped voltage source converter in a medium-voltage offshore wind power system under unbalanced grid conditions. The proposed control algorithm particularly compensates for the unbalanced grid voltage at the point of common coupling in a collector bus of offshore wind power system. This control algorithm has been formulated based on the symmetrical components in positive and negative rotating synchronous reference frames under generalized unbalanced operating conditions. Instantaneous active and reactive power are described in terms of symmetrical components of measured grid input voltages and currents. Negative sequential component of ac input current is injected to the point of common coupling in the proposed control strategy. The amplitude of negative sequential component is calculated to minimize the negative sequential component of grid voltage under the limitation of current capability in a voltage source converter. The proposed control algorithm makes it possible to provide a balanced voltage at the point of common coupling resulting in the generated power of high quality from offshore wind power system under unbalanced network conditions.

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Control Strategy Compensating for Unbalanced Grid Voltage Through Negative Sequence Current Injection in PMSG Wind Turbines

  • Kang, Jayoon;Park, Yonggyun;Suh, Yongsug;Jung, Byoungchang;Oh, Juhwan;Kim, Jeongjoong;Choi, Youngjoon
    • Proceedings of the KIPE Conference
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    • pp.244-245
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    • 2013
  • This paper proposes a control algorithm for permanent magnet synchronous generator with a back-to-back three-level neutral-point clamped voltage source converter in a medium-voltage offshore wind power system under unbalanced grid conditions. The proposed control algorithm particularly compensates for the unbalanced grid voltage at the point of common coupling in a collector bus of offshore wind power system. This control algorithm has been formulated based on the symmetrical components in positive and negative rotating synchronous reference frames under generalized unbalanced operating conditions. Instantaneous active and reactive power are described in terms of symmetrical components of measured grid input voltages and currents. Negative sequential component of ac input current is injected to the point of common coupling in the proposed control strategy. The amplitude of negative sequential component is calculated to minimize the negative sequential component of grid voltage under the limitation of current capability in a voltage source converter. The proposed control algorithm makes it possible to provide a balanced voltage at the point of common coupling resulting in the generated power of high quality from offshore wind power system under unbalanced network conditions.

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Power Quality Impacts of an Electric Arc Furnace and Its Compensation

  • Esfandiari Ahmad;Parniani Mostafa;Mokhtari Hossein
    • Journal of Electrical Engineering and Technology
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    • v.1 no.2
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    • pp.153-160
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    • 2006
  • This paper presents a new compensating system, which consists of a shunt active filter and passive components for mitigating voltage and current disturbances arising from an Electric Arc Furnace (EAF). A novel control strategy is presented for the shunt active filter. An extended method based on instantaneous power theory in a rotating reference frame is developed for extraction of compensating signals. Since voltages at the point of common coupling contain low frequency interharmonics, conventional methods cannot be used for dc voltage regulation. Therefore, a new method is introduced for this purpose. The passive components limit the fast variations of load currents and mitigate voltage notching at the Point of Common Coupling (PCC). A three-phase electric arc furnace model is used to show power quality improvement through reactive power and harmonic compensation by a shunt active filter using the proposed control method. The system performance is investigated by simulation, which shows improvement in power quality indices such as flicker severity index.

Design and Implementation of Instantaneous Power Estimation Algorithm for Unified Power Conditioner

  • S., Sindhu;M.R., Sindhu;Nambiar, T.N.P.
    • Journal of Power Electronics
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    • v.19 no.3
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    • pp.815-826
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    • 2019
  • This paper discusses a simple control approach for a Unified Power Conditioner (UPC) system to achieve power quality compensation at the point of common coupling in distribution systems. The proposed Instantaneous Power Estimation Algorithm (IPEA) for shunt and series active power filters uses a simple mathematical concept that reduces the complexity in the design of the controller. The performance of a UPC is verified with a system subjected to voltage distortions, sags/swells and unbalanced loads using MATLAB/SIMULINK. The simulation study shows that a UPC with the proposed control algorithm can effectively compensate for voltage and current harmonics, unbalance and reactive power. The control algorithm is experimentally implemented using dSPACE DS1104 and its effectiveness has been verified.

A Study on Harmonics Analysis and Modelling for Distribution System (배전 시스템의 고조파 분석 및 모델링에 관한 연구)

  • Wang, Yong-Peel;Jeong, Jong-Won;Jeong, Dong-Il
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.21 no.3
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    • pp.62-68
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    • 2007
  • The increasing use of power electronic equipment in distribution system has been the reason for the greater concern about a harmonic in recent time. Therefore, it is necessary for measurement and modelling to analyze a harmonic level and a transfer characteristic in distribution system. In this paper, the Point of Common Coupling (PCC) is selected to analyze harmonic characteristic of distribution system by IEC 61000-3-6. Harmonic voltage and orient were measured at the PCC of real distribution system Harmonic distribution, nonlinear load component and Total Harmonic Distortion(THD) were verified. The effective and accurate modelling of real distribution system were proved through a analysis of harmonic impedance, voltage and current under steady-state. Harmonic transfer characteristic were investigated through a analysis of harmonic voltage and current under harmonic current source.

Optimal Measurement Placement for VTHD level presentation in Distribution Systems (배전계통의 VTHD레벨 제시를 위한 최적측정위치 선정)

  • Park, Hee-Chul;Cho, Num-Hun
    • Proceedings of the KIEE Conference
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    • pp.378-380
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    • 2003
  • This paper presents the optimal point for measuring harmonic levels in distribution systems. Harmonic should be measure PCC (Point of Common Coupling), where is extended over distribution systems, but some PCCs are limited for economical and technical reason : for this reason, the harmonic measurement for a real distribution system and computer simulation are performed to find the optimal PCC in this paper.

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Firing Angle Control of Soft Starter for Reduction of Inrush Current during Induction Generator to Gird (유도발전기 계통 연계시 돌입전류 저감을 위한 소프트 스타터 점호각 제어)

  • Kwon Tae-Hwa;Song Seung-Ho
    • Proceedings of the KIPE Conference
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    • pp.230-233
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    • 2003
  • Simulation model of induction type fixed speed wind power generator is developed. It is shown that the peak value of inrush current during start up changes according to the firing angle control strategy of soft starter. New proposed firing angle control scheme showed $25\%$ of reduction of peak current which results in smaller drop of gird voltage at the point of common coupling during start up.

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Study of Harmonic Sources Management Method using Control Chart (컨트롤 차트를 이용한 고조파 전압 왜곡 발생원 관리기법 연구)

  • Han, Jong-Hoon;Lee, Key-Byung;Jang, Gil-Soo;Park, Chang-Hyun
    • Proceedings of the KIEE Conference
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    • pp.197-198
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    • 2011
  • A technique to manage harmonic pollution at the point of common coupling (PCC) has been presented using a control chart. The recursive least-squares technique has been used to estimate the parameters of the Thevenin equivalent load model. With the estimated data from the measured voltage and current waveform at the PCC during certain period violating upper control limit, the individual contributions to the distortion of voltage waveform at an interested harmonic frequency have been calculated and shown by simple graph.

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