The grid-connection point of photovoltaic inverters may exhibit inductive characteristics (i.e., a weak grid) due to long transmission cables as well as multiple transformers. A large grid impedance can arouse impedance-based stability problems, sustained resonances and impose power-delivery limits. This paper discusses an impedance-compensated synchronous reference- frame-PLL-angle-correction method. The method presented in this paper compensates the PLL angle according to estimated or measured grid impedance in order to achieve improved performance in weak grids. Due to the lack of explicit small-signal impedance models around the aforementioned topic, this paper presents a complete small-signal transfer function model to analyze the impedance-based stability of the PLL-angle compensation method. The results are validated with real-time hardware-in-the-loop simulations and laboratory experiments.

中文翻译：

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弱电网阻抗补偿锁相环光伏逆变器小信号分析

由于传输电缆较长以及多个变压器，光伏逆变器的并网点可能会表现出电感特性（即弱电网）。大的电网阻抗会引起基于阻抗的稳定性问题、持续谐振并施加功率输送限制。本文讨论了一种阻抗补偿同步参考框架锁相环角度校正方法。本文提出的方法根据估计或测量的电网阻抗补偿 PLL 角度，以提高弱电网中的性能。由于围绕上述主题缺乏明确的小信号阻抗模型，本文提出了一个完整的小信号传递函数模型来分析基于阻抗的 PLL 角度补偿方法的稳定性。