• Title/Summary/Keyword: Harmonics and reactive power

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Modeling and Analysis of Control Scheme for Voltage Source Inverter Based Grid-connection of Wind Turbine (전압원인버터를 이용한 계통연계형 풍력발전의 출력제어 모의 및 해석)

  • 김슬기;김응상
    • Journal of Energy Engineering
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    • v.12 no.2
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    • pp.154-163
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    • 2003
  • Grid connection essentially requires a wind energy conversion system (WECS) to not only supply adequate power responding to constantly varying wind speed but also provide a specified level of voltage magnitude and frequency that is acceptable in the electric power network. To satisfy such requirements, appropriate control schemes of a wind turbine to be connected to the power grid should be employed. This paper presents an output control strategy of a grid-connected wind power generation, which consists of a fixed-pitch wind turbine, a synchronous generator and a AC-DC-AC component with a voltage source inverter built in, and performs modelling and analysis of the strategy using PSCAD/EMTDC, an electromagnetic transient analysis software. Real power output control of the voltage source inverter is implemented to extract the maximum energy from wind speed inputted through wind blades and reactive power control, to keep the terminal voltage of WECS at a specific level. SPWM switching method is used to reduce the harmonics and maintain 60 ㎐ of the output frequency. The wind turbine performance and output corresponding to wind variation and the terminal load change is simulated and analysed.

A Study on the Static Var Compensator Application for the train garage in Korean National Railroad: Analysis of Harmonic Generation of SVC (전동차 사무소의 SVC 적용에 따른 고조파 발생에 관한 연구)

  • Lee, Seung-Hyuk;Lee, Jun-Kyong;Kim, Jin-O
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.18 no.3
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    • pp.101-108
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    • 2004
  • AC electric railroad system receives its power from 3-phase transmission system, Since, trainloads are changing continuously, the voltages for the single-phase load fluctuate in the train garage, and moreover, the fluctuating voltages generate high-order harmonics. This means that there is the difficulty in maintaining power quality in the power system. Therefore, a Static Var Compensator(SVC), which in general compensates the reactive power, is used in order to balance the trainload. In this paper, PSCAD/EMTDC is used for the analysis of harmonic generation in the train garage using SVC. The Total Harmonic Distortion(THD) of voltages is calculated using PSCAD/EMTDC dynamic simulation. As a result, the train garage using SVC improves power quality.