考虑频率耦合及交直流端口耦合效应的并网变流器三端口导纳模型

Three-port Admittance Modeling of Grid-connected Converters Considering Frequency-coupling and AC/DC Coupling Effects

三相并网变流器的阻抗/导纳建模对分析系统稳定性具有重要意义。传统研究大多只关注变流器的交流侧频率耦合效应和内环控制动态,但很少关注变流器交直流端口间的耦合效应及外环动态。该文提出一种三相变流器的三端口导纳模型,可以同时计及交流侧频率耦合和变流器交直流端口间动态耦合的影响,并使得各端口自身的小信号动态建模过程更为直观。通过所得模型展示了交直流耦合和频率耦合对系统稳定性的显著影响,并结合时域仿真验证了所提模型的准确性。

The impedance/admittance modeling of the three-phase voltage-source converter(VSC)is of great importance for the stability analysis of renewable power systems.Most previous work focused on the frequency-coupling effects and converter inner-loop current control dynamics,but paid little attention to couplings between AC and DC networks or outer-loop control dynamics.This paper proposed a novel admittance model of VSC,namely the three-port admittance model.It was capable of capturing the couplings between frequencies and between AC/DC networks in the same admittance matrix.Meanwhile,the modeling of each port’s dynamics could be carried out more intuitively.Based on this model,the impacts from coupling effects on system stability could be quantified.The effectiveness of the proposed model was validated using time-domain simulations.