采用基于频域调制的谐波平衡法进行交直流系统的谐波分析

为定性定量地研究HVDC的谐波问题以及谐波与系统的相互作用，对HVDC中换流站的模型和换流站与交流系统之间的联系在谐波域中进行了分析，采用频域内求解调制过程与谐波平衡相结合的方法来计算系统中的谐波分布。并具体针对HVDC内特定的不同负荷、三相不平衡以及换流站电压混杂谐波分量的情况进行了分析，得到交直流系统中存在的特征谐波和非特征谐波的相关性态。结果表明，这种分析方法采用模块化结构，系统性强，能有效地将各个非线性谐波源分离。为分析多个谐波源的复杂系统提供了有效的工具。

Analysis on Harmonics of AC-DC System Using Harmonic-balance Method Based on Modulation Theory

In order to analyze harmonics of HVDC/AC systems, this paper describes the model of the converter with its switching function and analyses the interaction between AC and DC system in harmonic domain. A method named modulation and harmonics-balance in frequency domain is proposed. This method can separate the non-linear parts and the AC system effectively. This paper also gives examples of calculating the harmonics in the events of different loads, harmonics and their negative sequence components in the AC voltage, analyses characteristic and non-characteristic harmonics of AC-DC system. This method can be applied in complex harmonic system analysis, especially in system with several harmonic sources.