基于谐波线性化的单相变换器改进镜像频率阻抗建模与稳定性分析

Improved Mirror Frequency Impedance Modeling and Its Stability Analysis for Single-phase Converter Based on Harmonic Linearization

高铁动车组内部电力电子装置呈现出强耦合性与时变非线性特征,与牵引网阻抗的复杂交互使得牵引网侧电压电流出现低频振荡的不稳定现象。传统dq阻抗分析方法存在物理意义不明显、测量与建模较为复杂的缺点;而基于谐波线性化的传统镜像频率阻抗分析方法存在低频处建模不准确的缺点。针对这些问题,该文以CRH5型车为研究对象,提出一种单相变换器的改进镜像频率阻抗模型,分析了谐波在单相变换器中的产生机理与传递规律,阐述了系统参数对于低频振荡的影响机理。基于MatlabSimulink仿真平台,将该模型与传统3种镜像频率阻抗进行了对比,验证了该模型的准确性;最后,基于StarsimHIL半实物平台,对理论分析的结果进行了验证,进一步证明了该模型对于研究单相系统低频稳定性的有效性。

The power electronic devices in the electric multiple units(EMUs) often prensent strong coupling and time-varying nonlinear characteristics. The complex interaction between the devices and the impedance of the traction network makes the voltage and current oscillate at low frequency. The traditional dq impedance analysis exists the defects of unclear physical significance and the complicated measuring and modeling. The traditional mirror frequency impedance analysis based on harmonic linearization has the disadvantage of inaccurate modeling at low frequencies. To solve these problems, an improved mirror frequency impedance model of single-phase converter is proposed in this paper, taking the CRH5 EMUs as the research object. The generation mechanism and transmission law of harmonics in the single-phase converter are analyzed, and the influence mechanism of parameters on the low-frequency oscillation is expounded. Based on the MatlabSimulink platform, the proposed model is compared with three traditional mirror frequency impedances, verifying the accuracy of the proposed model. Finally, the theoretical analysis results are carried out via the StarsimHIL semi-physical platform, which further proves the validity of the model of the research for the low-frequency stability.