考虑频率耦合特性的VSC序阻抗建模

基于序阻抗模型的稳定性理论在并网电压源换流器(Voltage Source Converter,VSC)系统稳定性分析中得到了广泛应用.为了更准确地描述VSC的外部阻抗特征,提高稳定性分析的准确性,文章将锁相环和直流母线的非理想特性引入到VSC序阻抗建模过程中.首先,分析了这二者对序阻抗的影响,指出这二者使得序阻抗中含...

Sequence impedance modeling of VSC considering frequency couplings

The stability theory based on sequence impedance model has been widely used in the stability analysis of grid-connected voltage source converter (VSC) systems. In order to describe the external impedance characteristics of VSC more accurately and improve the accuracy of stability analysis, this paper introduces the non-ideal characteristics of phase locked loop (PLL) and dc bus into VSC sequence impedance modeling. Firstly, the effects of these two factors on the impedance are analyzed, the results show that there exist frequency coupling terms caused by these two factors in the sequence impedance. Then, the sequence impedance model of VSC considering the frequency couplings is derived, and the accuracy of the model is verified by simulation. The effects of PLL parameters and dc link voltage controller parameters on the coupling terms are studied, the results show that the frequency coupling phenomenon is obvious in the low frequency range, and the coupling strength can be reduced by appropriately selecting parameters.