Advanced digital filter is important for grid voltage synchronization, harmonic information extraction, and converter control. The complex variable filter (CVF) such as the reduced order generalized integrator is one of the most prevalent filters. However, it is proven in this paper that the real coefficient CVF achieves performance identical to the real variable filter such as the second-order generalized integrator. It implies that the advantages of CVF are not fully utilized. Therefore, in this paper, the real coefficient is extended to a complex one leading to a complex coefficient CVF (CC-CVF), and the filter performance of CVF for extracting the harmonics is significantly improved. Furthermore, linear quadratic regulation is employed to design the complex coefficients to achieve a better dynamic performance. Finally, the CC-CVF is enhanced with frequency estimation capability. The proposed CC-CVF is verified by extensive simulations and experiments.

中文翻译：

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基于线性二次调节的电网同步复系数复变滤波器


先进的数字滤波器对于电网电压同步、谐波信息提取和转换器控制非常重要。诸如降阶广义积分器之类的复变量滤波器（CVF）是最流行的滤波器之一。然而，本文证明实系数CVF 实现了与二阶广义积分器等实变量滤波器相同的性能。这意味着CVF的优势没有得到充分发挥。因此，本文将实数系数扩展为复数系数，得到复数系数CVF（CC-CVF），并且CVF提取谐波的滤波性能得到显着提高。此外，采用线性二次调节来设计复系数以实现更好的动态性能。最后，CC-CVF 的频率估计能力得到增强。所提出的 CC-CVF 通过大量的模拟和实验得到验证。