考虑谐波耦合的多变流器并网系统建模及交直流谐波交互特性分析

新型电力系统中高比例可再生能源和高比例电力电子设备接入的特征带来异于传统电网下的谐波交互问题，多变流器拓扑的谐波耦合交互特性亟待研究。首先，基于谐波状态空间(harmonic state space, HSS)对多变流器并网系统(multiple grid-connected-converter system, MGCCS)建立考虑谐波耦合的谐波传递函数矩阵模型，综合考虑了系统各控制环节对状态变量的影响以及变流器的级联、并联。其次，基于所建HSS模型明确定义谐波耦合系数，并用于揭示多变流器拓扑的谐波耦合机理，分析级联、并联变流器谐波交互特性。然后，应用谐波耦合系数量化分析MGCCS中滤波电感、电流环、锁相环等关键参数对系统谐波交互的影响。最后，将HSS模型和Matlab/Simulink模型、RT-LAB模型的结果进行对比，验证了所建HSS模型的精确性，以及谐波耦合系数理论应用于系统交直流谐波交互分析的有效性。

Modeling of a multiple grid-connected-converter system considering harmonic coupling and analysis of AC/DC harmonic interaction characteristics

The characteristics of high penetration of renewable energy and high proportion of power electronic equipment in new power systems bring a harmonic interaction problem. This is different from traditional power systems. The harmonic coupling interaction characteristics of the multi-converter topology need to be studied. First, based on the harmonic state space (HSS), the harmonic transfer function matrix model considering harmonic coupling is established for the multiple grid-connected-converter system (MGCCS). The model comprehensively considers the influence of each control link of the system on the state variables as well as the factors of cascade and parallel converters. Second, the harmonic coupling coefficient is defined based on the established HSS model. This is used to reveal the harmonic coupling mechanism of the multi-converter topology, and analyze the harmonic interaction characteristics of the cascade and parallel converters. Then, the harmonic coupling coefficient is used to quantify the influence of key parameters such as filter inductor, current loop and phase-locked loop on the harmonic interaction of MGCCS. Finally, the results of the HSS model, Matlab/Simulink model and RT-LAB model are compared to verify the accuracy of the proposed HSS model and the effectiveness of the harmonic coupling coefficient theory applied to the AC/DC harmonic interaction analysis of the system.