Grid-tied inverters, used in renewable energy sources, are exposed to distortions emitted by various sources including the reference signal, external power grid, and DC-link along with harmonics created by the pulse width modulation unit. However, the effect of these sources on grid-tied inverter output, especially near the resonant frequency of the inverter's filter, is unknown. In this study, a comprehensive harmonic model of the grid-tied inverter is presented by considering all three types of external sources. The proposed model can be utilised for low and high-frequency harmonic emission of grid-connected inverters. A new analytical expression is introduced as an indicator of the maximum possible individual grid current harmonic in the case of harmonic injection of multiple external sources. The impact of series damping resistor on harmonic rejection ability of the inverter is analysed at the range of frequencies around resonance. The simulation and experimental results fulfil the proposed harmonic model of the inverter.

中文翻译：

---

考虑外部失真的并网逆变器的谐波分析：解决高达9 kHz的谐波发射

用于可再生能源的并网逆变器会受到各种来源发射的失真的影响，这些来源包括参考信号，外部电网和直流母线以及脉宽调制单元产生的谐波。但是，尚不清楚这些源对并网逆变器输出的影响，尤其是在逆变器滤波器的谐振频率附近。在这项研究中，通过考虑所有三种外部源，提出了并网逆变器的综合谐波模型。该模型可用于并网逆变器的低频和高频谐波发射。引入了一个新的分析表达式，作为在多个外部源进行谐波注入的情况下最大可能的单个电网电流谐波的指标。在谐振附近的频率范围内，分析了串联阻尼电阻对逆变器谐波抑制能力的影响。仿真和实验结果满足了提出的逆变器谐波模型。