Impedance Characteristic

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đani Juricic - One of the best experts on this subject based on the ideXlab platform.

Andrej Debenjak - One of the best experts on this subject based on the ideXlab platform.

Heng Nian - One of the best experts on this subject based on the ideXlab platform.

  • analysis and reshaping on Impedance Characteristic of dfig system based on symmetrical pll
    IEEE Transactions on Power Electronics, 2020
    Co-Authors: Heng Nian, Liang Chen, Frede Blaabjerg
    Abstract:

    With the increasing penetration of renewable energy, wind turbines based on doubly fed induction generators (DFIG) are becoming more and more important in the power system. The Impedance reshaping control strategy based on the virtual Impedance method can be utilized to solve the stability problem of the DFIG-grid interconnected system under the weak grid. However, the stability issues caused by phase-locked loop (PLL) is more complicated due to the frequency coupling Characteristic. This article presents an improved control strategy of the DFIG system based on a symmetrical PLL, in which the frequency coupling Characteristic can be avoided and the system can be simplified as a single-input single-output system that facilitates the design of virtual Impedance. The influence of symmetrical PLL on the operation of the DFIG system is studied, and an improved Impedance reshaping control strategy is proposed. Simulation and experimental results are conducted to verify the effectiveness of the proposed Impedance reshaping control strategy.

  • Harmonic Impedance Modeling of DFIG Considering Dead Time Effect of Rotor Side Converter
    2018 IEEE Energy Conversion Congress and Exposition (ECCE), 2018
    Co-Authors: Chao Wu, Heng Nian, Peng Cheng, Qi Zhou, Bo Pang
    Abstract:

    This paper proposes a novel harmonic Impedance modeling method of doubly fed induction generator (DFIG) considering the dead time effect. The dead time of the rotor side converter (RSC) will induce distorted voltage to the rotor side of DFIG. By obtaining the transfer function from stator voltage and rotor distorted voltage to stator current, the admittance of RSC+DFIG can be deduced. Considering that the harmonic currents caused by the dead time work as a current source, the Norton equivalent circuit of RSC+DFIG can be obtained. In this way, the harmonic currents not only caused by the grid harmonic voltages but also the dead time effect can be both accurately acquired, which is very useful for the harmonic currents analysis for wind farm. Furthermore, the Impedance Characteristic of RSC+DFIG is also obtained which is useful for harmonic resonance analysis. Finally, the correctness of the equivalent circuit and stator harmonic currents is validated by the simulation results.

Bojan Musizza - One of the best experts on this subject based on the ideXlab platform.

Janko Petrovčič - One of the best experts on this subject based on the ideXlab platform.