高频谐波扰动下直流电网阻抗模型特征分析

直流配电网故障发展迅速且无固定频率的故障特征分量,因此,其故障特征的准确解析有重要的研究意义。从直流故障状态下系统阻抗特性分析出发,重点研究各类直流换流器的频率-阻抗响应。基于DC/DC变换器和模块化多电平换流器谐波通路,根据元件参数特性进行合理等效与简化,建立了上述变换器的高频阻抗模型。所述模型不受换流器控制策略影响,能够精确反映各类换流器的高频阻抗特性。

Characteristic Analysis on Impedance Model of DC Grid with High-frequency Harmonic Disturbance

The faults of DC distribution network develop rapidly and the frequency of fault components are not constant, thus the accurate analysis on fault characteristics has important research significance. From the perspective of impedance characteristic analysis in DC fault conditions, the frequency-impedance responses of various DC converters are studied. Based on the harmonic path of DC/DC converter and modular multilevel converter (MMC), reasonable equivalence and simplification are carried out according to the component parameter characteristics, and the high-frequency impedance models of the converters are established. The proposed model will not be affected by the inverter control strategy, and can accurately reflect the high-frequency impedance characteristics of various types of converters.