TY - JOUR
T1 - MMC Admittance Model Simplification Based on Signal-Flow Graph
AU - Xu, Zigao
AU - Li, Binbin
AU - Li, Shengyuan
AU - Wang, Xiongfei
AU - Xu, Dianguo
PY - 2022/5
Y1 - 2022/5
N2 - Although the impedance/admittance model of modular multilevel converter (MMC) considering internal harmonic is discussed extensively in the literature, few attentions have been focused on how to determine the number of harmonics to be included in the model. This article fills this gap by developing the MMC signal-flow graph (SFG), providing the analytical transfer function to quantitatively estimate the attenuation degree of MMC harmonics, so as to guide the model truncation. Besides, SFG offers an intuitive understanding on the mathematical characteristic of MMC, including the conjugate symmetry and the effect of phase reference on admittance, which helps to reduce the modeling calculation. Moreover, conversion formula of MMC multiple input multiple output and single input single output admittance is derived based on the truncated model to further simplify the stability analysis. The correctness of this article has been verified by simulation and experiment.
AB - Although the impedance/admittance model of modular multilevel converter (MMC) considering internal harmonic is discussed extensively in the literature, few attentions have been focused on how to determine the number of harmonics to be included in the model. This article fills this gap by developing the MMC signal-flow graph (SFG), providing the analytical transfer function to quantitatively estimate the attenuation degree of MMC harmonics, so as to guide the model truncation. Besides, SFG offers an intuitive understanding on the mathematical characteristic of MMC, including the conjugate symmetry and the effect of phase reference on admittance, which helps to reduce the modeling calculation. Moreover, conversion formula of MMC multiple input multiple output and single input single output admittance is derived based on the truncated model to further simplify the stability analysis. The correctness of this article has been verified by simulation and experiment.
KW - Conjugate symmetry
KW - Harmonic attenuation ratio (HAR)
KW - Phase dependence
KW - Signal-flow graph (SFG)
KW - Simplification
UR - http://www.scopus.com/inward/record.url?scp=85123983274&partnerID=8YFLogxK
U2 - 10.1109/TPEL.2021.3126870
DO - 10.1109/TPEL.2021.3126870
M3 - Journal article
SN - 0885-8993
VL - 37
SP - 5547
EP - 5561
JO - IEEE Transactions on Power Electronics
JF - IEEE Transactions on Power Electronics
IS - 5
ER -