• Title, Summary, Keyword: AC/DC hybrid simulation

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Development of AC/DC Hybrid Simulation for Operator Training Simulator in Railway System

  • Cho, Yoon-Sung;Lee, Hansang;Jang, Gilsoo
    • Journal of Electrical Engineering and Technology
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    • v.9 no.1
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    • pp.52-59
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    • 2014
  • Operator training simulator, within a training environment designed to understand the principles and behavior of the railway system with respect to operator's entries and predefined scenario, can provide a very strong benefit in facilitating operators' handling undesired operations. This simulator consists of computer system and applications, and the purpose of applications is to generate the power and voltage and analyze the AC substation and DC railway, respectively. This paper describes a novel approach to the new techniques for AC/DC hybrid simulation for the operator training simulator in the railway system. We first propose the structure the database of railway system. Then, topology processing and power flow using a linked-list method based on the proposed database, full or decoupled newton-rapshon methods are presented. Finally, the interface between the analysis for AC substation using a newton-rapshon method and the analysis for DC railway system using a time-interval power flow method is described. We have verified and tested the developed algorithm through the extensive testing for the proposed test system. To demonstrate the validity of the developed algorithm, comparative simulations between the proposed algorithm and PSS/E for the test system were conducted.

Operation and Performance Analysis of New Bidirectional Intelligent Semiconductor Transformer (새로운 양방향 지능형 반도체 변압기의 동작과 성능 분석)

  • Kim, Do-Hyun;Lee, Byung-Kwon;Han, Byung-Moon;Lee, Jun-Young;Choi, Nam-Sup
    • The Transactions of the Korean Institute of Power Electronics
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    • v.18 no.2
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    • pp.169-177
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    • 2013
  • This paper proposes a new configuration of bidirectional intelligent semiconductor transformer with rating of 1.9kV/127V, 2kVA. The proposed transformer consists of high-voltage high-frequency AC-DC rectifier, and low-voltage DC-DC and DC-AC converters. The operational feasibility of proposed transformer was verified by computer simulation with PSCAD/EMTDC software. Based on the simulation results, a hardware prototype with rating of 1.9kV/127V, 2kVA was built and tested in the lab to confirm the feasibility of hardware implementation. Using three units of this transformer, a 3-phase transformer with rating of 3.3kV/220V, 6kVA can be built.

Current Limiting and Interrupting Operation of Hybrid Self-Excited Type Superconducting DCCB

  • Choi, S.J.;Lim, S.H.
    • Progress in Superconductivity and Cryogenics
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    • v.20 no.4
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    • pp.55-59
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    • 2018
  • Currently, the development of industry makes needs larger electric supply. Providers must consider the efficiency about losses and reliability of the system. In this case, DC power system can save electrical energy; long-distance transmission line losses. Relevance to switch technology with a voltage-source converter (VSC) in AC-DC conversion system have been researched. But, protection device of DC-link against fault current is still needed to study much. VSC DC power system is vulnerable to DC-cable short-circuit and ground faults, because DC-link has a huge size of capacitor filter which releases extremely large current during DC faults. Furthermore, DC has a fatal flaw that current zero crossing is nonexistence. To interrupt the DC, several methods which make a zero crossing is used; parallel connecting self-excited series LC circuit with main switch, LC circuit with power electronic device called hybrid DC circuit breaker. Meanwhile, self-excited oscillator needs a huge size capacitor that produces big oscillation current which makes zero crossing. This capacitor has a quite effective on the price of DCCB. In this paper, hybrid self-excited type superconducting DCCB which are using AC circuit breaker system is studied by simulation tool PSCAD/EMTDC.

Modeling of Hybrid Generation System with Wind Turbine, Diesel Generator and Flywheel Energy Storage System (풍력-디젤-플라이휘일 하이브리드 발전시스템 모델링에 관한 연구)

  • Kim, Jae-Eon
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.14 no.6
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    • pp.2979-2984
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    • 2013
  • This paper proposes a modeling and controller design method of Flywheel Energy Storage System(FESS) for solving the unstable operation problem in hybrid generation system with wind turbine and diesel generator applied in island area. FESS is considered as a permanent magnetic synchronous machine connected to flywheel because of its efficiency. The controller of FESS is composed of AC/DC/AC back-to-back converter. The AC/DC converter is designed to charge/discharge according to the frequency variation and the DC/AC converter to operate to keep the DC bus voltage constant. The proposed modeling and controller design method of FESS was applied to hybrid generation system with wind turbine and diesel generator. The unstable operation problem owing to wind variations was solved through simulation results.

Design and Implementation of Modified Current Source Based Hybrid DC - DC Converters for Electric Vehicle Applications

  • Selvaganapathi, S.;Senthilkumar, A.
    • Transactions on Electrical and Electronic Materials
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    • v.17 no.2
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    • pp.57-68
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    • 2016
  • In this study, we present the modern hybrid system based power generation for electric vehicle applications. We describe the hybrid structure of modified current source based DC - DC converters used to extract the maximum power from Photovoltaic (PV) and Fuel Cell system. Due to reduced dc-link capacitor requirement and higher reliability, the current source inverters (CSI) better compared to the voltage source based inverter. The novel control strategy includes Distributed Maximum Power Point Tracking (DMPPT) for photovoltaic (PV) and fuel cell power generation system. The proposed DC - DC converters have been analyzed in both buck and boost mode of operation under duty cycle 0.5>d, 0.5<d<1 and 0.5<d for capable electric vehicle applications. The proposed topology benefits include one common DC-AC inverter that interposes the generated power to supply the charge for the sharing of load in a system of hybrid supply with photovoltaic panels and fuel cell PEM. An improved control of Direct Torque and Flux Control (DTFC) based induction motor fed by current source converters for electric vehicle.In order to achieve better performance in terms of speed, power and miles per gallon for the expert, to accepting high regenerative braking current as well as persistent high dynamics driving performance is required. A simulation model for the hybrid power generation system based electric vehicle has been developed by using MATLAB/Simulink. The Direct Torque and Flux Control (DTFC) is planned using Xilinx ISE software tool in addition to a Modelsim 6.3 software tool that is used for simulation purposes. The FPGA based pulse generation is used to control the induction motor for electric vehicle applications. FPGA has been implemented, in order to verify the minimal error between the simulation results of MATLAB/Simulink and experimental results.

A Novel Variable-Speed Renewable-Energy Generation System of Induction Generator and PWM Converter for Small-Scale Hybrid Power Applications

  • Ahmed, Tarek;Nishida, Katsumi;Lee, Hyun-Woo;Nakaoka, Mutsuo
    • Proceedings of the KIEE Conference
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    • pp.1339-1342
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    • 2005
  • This paper presents a simple AC-DC power conditioner for a squirell-cage induction generator(IG) operating under variable shaft speeds. The necessary reactive power for the IG system is supplied by means of a capacitor bank and a voltage-source PWM converter. Using a capacitor bank to transfer the reactive power to the IG under the rated speed and no-load conditions starts the IG operation and reduces the PWM power converter size. A simple control compensating for changes in the electrical loads as well as the variation in speed was developed to regulate the voltages of the IG system by controlling the rotor flux through its reactive and active currents control implementation. This proposed power conditioning scheme can be used efficiently as a wind power generation system where the output voltage of the IG is maintained constant voltage despite the variable frequency and the DC bus voltage of the PWM converter can be used for either DC applications such as battery charging or AC power applications with 60/50 Hz by connecting a stand alone inverter. The experimental and simulated operating performance results of a 5 kW IG scheme at various speeds and leads are presented.

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Investigation of a Hybrid HVDC System with DC Fault Ride-Through and Commutation Failure Mitigation Capability

  • Guo, Chunyi;Zhao, Chengyong;Peng, Maolan;Liu, Wei
    • Journal of Power Electronics
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    • v.15 no.5
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    • pp.1367-1379
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    • 2015
  • A hybrid HVDC system that is composed of line commutated converter (LCC) at the rectifier side and voltage source converter (VSC) in series with LCC at the inverter side is studied in this paper. The start-up strategy, DC fault ride-through capability, and fault recovery strategy for the hybrid HVDC system are proposed. The steady state and dynamic performances under start-up, AC fault, and DC fault scenarios are analyzed based on a bipolar hybrid HVDC system. Furthermore, the immunity of the LCC inverter in hybrid HVDC to commutation failure is investigated. The simulation results in PSCAD/EMTDC show that the hybrid HVDC system exhibits favorable steady state and dynamic performances, in particular, low susceptibility to commutation failure, excellent DC fault ride-through, and fast fault recovery capability. Results also indicate that the hybrid HVDC system can be a good alternative for large-capacity power transmission over a long distance byoverhead line.

Improvement of Battery Charging Efficiency of ESS for Wind Power Application Using DC-AC Hybrid Charging Pattern (직교류 합성 충전 패턴을 이용한 풍력 연계용 ESS의 배터리 충전 효율 향상)

  • Lee, Jong-Hak;Song, Seung-Ho
    • The Transactions of the Korean Institute of Power Electronics
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    • v.22 no.4
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    • pp.330-335
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    • 2017
  • Increased fossil fuel consumption causes global warming, environmental pollution, and abnormal climate change. Wind-generated power installation is proposed to solve this problem. Recently, the wind power plant construction case encourages the installation of the energy storage system (ESS) to improve the intermittency of wind power. The maximized ESS operation profits connected to wind power are not generated in the simplest operation pattern of charging at night and discharging at day. The battery charging efficiency improvement should be considered to get more profits. Thus, there is a possibility of increasing ESS operation profits by analyzing the battery AC and DC charging/discharging efficiency and the yearly average sealed maintenance free (SMP) in hours. In this paper, the battery impedance characteristic, AC and DC charging/discharging efficiency, and the yearly average SMP are analyzed. The operation scenario to improve the ESS battery charging efficiency connected to wind power is proposed and verified via simulation.

Battery Charging System for PHEV and EV using Single Phase AC/DC PWM Buck Converter

  • Lee, Jung-Hyo;Jung, Doo-Yong;Park, Sang-Hoon;Lee, Taek-Kie;Kim, Young-Ryul;Won, Chung-Yuen
    • Journal of Electrical Engineering and Technology
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    • v.7 no.5
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    • pp.736-744
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    • 2012
  • In this paper, a battery charging system for Plug-in Hybrid Electric Vehicle (PHEV) and Electric Vehicle (EV), and operation algorithm of charging system are introduced. Also, the proposed charging system uses commercial electricity in order to charge the battery of parked PHEV and 48V battery charging system with power factor controllable single phase converter for PHEV is investigated in this paper. This research verifies the power factor control of input and the converter output controlled by the charge control algorithm through simulation and experiment.