• 제목/요약/키워드: 전원계통

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A Study on the Harmonics and Voltage Sags Effect by the Series Resonant Filter Application for Personal Computer Loads (개인용 컴퓨터 부하의 직렬동조필터 적용에 의한 고조파 및 순간전압강하 영향에 관한 연구)

  • Seo, Beom-Gwan;Kim, Kyung-Chul;Lee, Il-Moo
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.20 no.8
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    • pp.36-41
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    • 2006
  • Computer Loads can be found in all of modern society. The switching mode power supplies used in personal computers are major sources of harmonic currents. Harmonic currents can cause lots of harmonic problems such as disruption in computer performance. A series resonant filter is very effective in harmonic reduction for personal computer loads. Voltage sags are short duration reductions in rms voltage. The main causes of voltage sags at faults, motor starting, and transformer energizing. Personal computers are another example of devices sensitive to voltage sags. A serious voltage sag at the terminals way lead mis-operation of the equipment. This paper presents an in depth analysis to evaluate the effect of harmonics reduction based on the IEC 61000-3-2 and the effect of voltage sag using ITI curve by applying a series resonant filter for personal computer loads.

Breakdown Characteristics Assess of Imitation-Air for Distribution Power Facilities (배전급 전력설비를 위한 제조공기의 절연성 평가)

  • Lee, Kwang-Sik;Do, Yeong-Hoei;Choi, Eun-Hyeok;Lee, Chang-Uk;Park, Kwong-Seoo;Kim, Lee-Kook
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.22 no.2
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    • pp.114-119
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    • 2008
  • With the improvement of industrial society, the high quality electrical energy, simplification of operation and maintenance, ensuring reliability are being required. We request urgently change a $SF_6$ for an environment friendly gas insulation material. In this paper the experiments of breakdown characteristics by pressure and gap change of Imitation-Air in model GIS(Gas Insulated Switchgear) were described. Also assess of breakdown characteristics about Imitation-Air and $SF_6$. It is considered in this paper that the results are fundamental data for electric insulation design of Distribution Power Facilities which will be studied and developed in the future. The pressure to be confronted to $SF_6$ gas 1[atm] for Distribution Power Facilities is Imitation-Air 3[atm]. And we could make an environment friendly gas insulation material with maintaining dielectric strength by Imitation-Air which generates a lower level of the global warming effect.

Comparison of Current Controllers of Grid-connected PCS for Distributed Resources (분산전원용 계통연계형 PCS의 전류제어기 비교)

  • Park, Jong-Hyoung;Jo, Teak-Hyun;Kim, Heung-Geun;Chun, Tae-Won;Nho, Eui-Cheol;Cha, Hon-Nyung
    • The Transactions of the Korean Institute of Power Electronics
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    • v.17 no.3
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    • pp.274-280
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    • 2012
  • In this paper, three current controllers for a grid-connected PCS using an LCL filter are compared and analyzed. Current controllers discussed in this paper are linear controllers such as PI (proportional-integral), PR (proportional-resonant), and DB (deadbeat) controller. Both transient and steady state responses of each controller are compared through both simulation and experiment. Although the DB controller has the fastest transient response and the lowest THD in the steady state, the DB controller has two cycles delay of current response in the steady state and has the stability problem which can be occurred due to variation of the system parameters. On the one hand the responses of PR controller are not much different from that of DB controller but the other hand that are not only strong to noise of grid current but also have smaller THD than PI controller. Considering the response time and stability issue of three controllers, the PR controller has the best performance among three controllers and thus can be strongly recommended as a current controller for a grid-connected PCS.

Design of Triple Loop Current Control for Auxiliary Power Unit of Fuel Cell Train having Grid Connected Inverter Function (계통 연계 기능을 갖는 연료전지 철도차량 보조전원장치의 삼중 루프 전류 제어기 설계)

  • Kwon, Il-Seob;Baek, Seung-Woo;Kim, Hag-Wone;Cho, Kwan-Yual
    • The Transactions of the Korean Institute of Power Electronics
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    • v.25 no.4
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    • pp.293-302
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    • 2020
  • This study proposes a triple-loop current control method for the auxiliary power unit of fuel cell trains. The auxiliary power unit of fuel cell trains has a grid-connected function when power is supplied to the utility grid. Moreover, the auxiliary power unit of trains has a 1500 V DC link voltage; thus, PWM frequency cannot be increased to a high frequency. Owing to this low PWM frequency condition, creating a triple-loop design is difficult. In this study, a triple-loop controller is developed for a capacitor voltage controller in standalone mode that operates as an auxiliary power supply for trains and for a grid current controller in grid control mode with an inner capacitor voltage controller. The voltage controller employs an inductor current controller inner loop. To overcome low PWM frequency, a design method for the bandwidth of the capacitor voltage controller considering the bandwidth of the inner inductor current controller is described. The effectiveness of the proposed method is proven using PSIM simulation.

Compensation of Unbalanced PCC Voltage in an Off-shore Wind Farm of PMSG Type Turbines (해상풍력단지에서의 PMSG 풍력발전기를 활용한 계통연계점 불평형 전원 보상)

  • Kang, Ja-Yoon;Han, Dae-Su;Suh, Yong-Sug;Jung, Byoung-Chang;Kim, Jeong-Joong;Park, Jong-Hyung;Choi, Young-Joon
    • The Transactions of the Korean Institute of Power Electronics
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    • v.20 no.1
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    • pp.1-10
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    • 2015
  • This paper proposes a control algorithm for permanent magnet synchronous generators with a back-to-back three-level neutral-point clamped voltage source converter in a medium-voltage off-shore wind power system under unbalanced grid conditions. Specifically, the proposed control algorithm compensates for unbalanced grid voltage at the PCC (Point of Common Coupling) in a collector bus of an off-shore wind power system. This control algorithm has been formulated based on symmetrical components in positive and negative synchronous rotating reference frames under generalized unbalanced operating conditions. Instantaneous active and reactive power is described in terms of symmetrical components of measured grid input voltages and currents. Negative sequential component of AC input current is injected into the PCC 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 enables the provision of balanced voltage at the PCC resulting in the high quality generated power from off-shore wind power systems under unbalanced network conditions.

A Study on Real-time State Estimation for Smart Microgrids (스마트 마이크로그리드 실시간 상태 추정에 관한 연구)

  • Bae, Jun-Hyung;Lee, Sang-Woo;Park, Tae-Joon;Lee, Dong-Ha;Kang, Jin-Kyu
    • 한국태양에너지학회:학술대회논문집
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    • 2012.03a
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    • pp.419-424
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    • 2012
  • This paper discusses the state-of-the-art techniques in real-time state estimation for the Smart Microgrids. The most popular method used in traditional power system state estimation is a Weighted Least Square(WLS) algorithm which is based on Maximum Likelihood(ML) estimation under the assumption of static system state being a set of deterministic variables. In this paper, we present a survey of dynamic state estimation techniques for Smart Microgrids based on Belief Propagation (BP) when the system state is a set of stochastic variables. The measurements are often too sparse to fulfill the system observability in the distribution network of microgrids. The BP algorithm calculates posterior distributions of the state variables for real-time sparse measurements. Smart Microgrids are modeled as a factor graph suitable for characterizing the linear correlations among the state variables. The state estimator performs the BP algorithm on the factor graph based the stochastic model. The factor graph model can integrate new models for solar and wind correlation. It provides the Smart Microgrids with a way of integrating the distributed renewable energy generation. Our study on Smart Microgrid state estimation can be extended to the estimation of unbalanced three phase distribution systems as well as the optimal placement of smart meters.

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Design of a Photovoltaic PCS with Compensation Control of Reactive Power and Unbalance Current in Three-phase systems (3상 시스템의 무효전력, 불평형 전류 보상 기능을 갖는 태양광 전력변환장치 설계)

  • Park, Sang-Min;Kim, Chang-Soon;Le, Dinh Vuong;Park, Minwon;Yu, In-Keun
    • Journal of Korea Society of Industrial Information Systems
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    • v.21 no.3
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    • pp.29-33
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    • 2016
  • Development of the distributed energy resources such as photovoltaic, wind, and fuel cell has increased rapidly due to the rising demand for clean energy utilization. On the other hand, the distribution system became complex and has problems such as degradation of power factor and current unbalance caused by power converters, reactive power and unbalanced loads. To solve these problems, this paper proposes a 3-phase 4-leg type power conditioning system with compensation control algorithm for the reactive power and unbalance current in distribution system using photovoltaic resource. It is simulated in PSCAD/EMTDC and the effectiveness is confirmed.

Development of TASS Code for Non-LOCA Safety Analysis Licensing Application (Non-LOCA 인허가 해석용 TASS 코드의 개발)

  • Yoon, Han-Young;Auh, Geun-Sun;Kim, Hee-Cheol;Kim, Joon-Sung;Park, Jae-Don
    • Nuclear Engineering and Technology
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    • v.27 no.1
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    • pp.53-66
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    • 1995
  • Since the current licensed system codes for Non-LOCA safety analysis are applicable only for a specific type PWR, it is necessary to develope a new system analysis code applicable for all apes of PWRs. As a R&D program, KAERI is developing TASS code as an interactive and faster-than-real-time code for the NSSS transient simulation of both CE and Westinghouse plane. It is flexible tool for PWR analysis which gives the user complete control over the simulation through convenient input and output options. In this paper the code applicability to Westinghouse ape plants was verified by comparing the TASS prediction to plant data of loss of AC power and loss of load transients, and comparing to the prediction of RELAP5/MOD3 for feedline break, locked rotor, steam generator tube rupture and steam line break accidents.

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A Study on Effects of Offset Error during Phase Angle Detection in Grid-tied Single-phase Inverters based on SRF-PLL (SRF-PLL을 이용한 계통연계형 단상 인버터의 전원 위상각 검출시 옵셋 오차 영향에 관한 연구)

  • Kwon, Young;Seong, Ui-Seok;Hwang, Seon-Hwan
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.29 no.10
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    • pp.73-82
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    • 2015
  • This paper proposes an ripple reduction algorithm and analyzes the effects of offset and scale errors generated by voltage sensor while measuring grid voltage in grid-tied single-phase inverters. Generally, the grid-connected inverter needs to detect the phase angle information by measuring grid voltage for synchronization, so that the single-phase inverter can be accurately driven based on estimated phase angle information. However, offset and scale errors are inevitably generated owing to the non-linear characteristics of voltage sensor and these errors affect that the phase angle includes 1st harmonic component under using SRF-PLL(Synchronous Reference Frame - Phase Locked Loop) system for detecting grid phase angle. Also, the performance of the overall system is degraded from the distorted phase angle including the specific harmonic component. As a result, in this paper, offset and scale error due to the voltage sensor in single-phase grid connected inverter under SRF-PLL is analyzed in detail and proportional resonant controller is used to reduce the ripples caused by the offset error. Especially, the integrator output of PI(Proportional Integral) controller in SRF-PLL is selected as an input signal of the proportional resonant controller. Simulation and experiment are performed to verify the effectiveness of the proposed algorithm.

Fault Diagnosis for 3-Phase Diode Rectifier using Harmonic Ripples of DC Link Voltage (직류단 전압의 고조파 맥동 검출을 이용한 3상 다이오드 정류기의 고장 진단)

  • Park, Je-Wook;Baek, Seong-Won;Kim, Jang-Mok;Lee, Dong-Choon;Lee, Kyo-Beum
    • The Transactions of the Korean Institute of Power Electronics
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    • v.16 no.5
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    • pp.457-465
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    • 2011
  • The fault analysis and detecting algorithm for a 3 phase diode rectifier is proposed. The 3 phase dioderectifier is used for the AC power rectifier of the PWM inverter. The input power or diode faults cause theripples of the DC voltage, degradation of the control performance and life shortening of the DC link capacitor.In this paper, the ripple of the DC voltage is mathematically analyzed for the earth fault of input power andopen circuit fault of the diode, respectively. The fault detection and type of fault can be obtained by comparingthe average DC voltage and the instant DC voltage which is sampled with 6 times of grid frequency. Theproposed method can be easily applicable and doesn't require additional circuit. The experimental and simulationresults are presented to verify the validity of the proposed method.