Grid-following voltage source converter (GFL-VSC) does not establish frequency like synchronous generator (SG), but follows the frequency of the terminal bus using phase-looked loop (PLL). This letter demonstrates that GFL-VSC also affects the terminal frequency, rather than simply follows it, due to the dynamics of the PLL and outer control loops. The relationship between PLL frequency, d-axis current, and terminal frequency is derived. Both the PLL frequency and the d-axis current affect the terminal frequency in the form of their derivatives, which is completely different from conventional SG and the corresponding frequency divider formula (FDF). Time-domain simulation results validate the derived relationship.

中文翻译：

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并网VSC对终端频率的影响

电网跟随电压源换流器（GFL-VSC）不像同步发电机（SG）那样建立频率，而是使用锁相环（PLL）跟随终端母线的频率。这封信表明，由于 PLL 和外部控制环路的动态，GFL-VSC 也会影响终端频率，而不是简单地跟随它。推导出PLL频率、d轴电流和端频率之间的关系。PLL频率和d轴电流都以其导数的形式影响终端频率，这与传统的SG和相应的分频器公式（FDF）完全不同。时域仿真结果验证了导出的关系。