Abstract The study investigates the oscillation stability determined by phase locked loops (PLLs) in a weakly grid-connected wind farm with multiple permanent magnet synchronous generators (PMSGs). To this end, an equivalent model of the wind farm is derived. Based on the derived equivalent model, the oscillation stability of the wind farm as determined by the dynamics of the PLLs is analytically examined. This paper explains why the PLLs equipped by the PMSGs in the wind farm can lead to instability risk under the condition of weak grid connection. A simple index is proposed to approximately assess instability risk of the wind farm due to the PLLs. The parametric model of the wind farm with the PMSGs is not necessary to calculate the proposed simple index. Hence, it is model-free and applicable in practice when it is difficult to establish the parametric model. An example of a grid-connected wind farm with 12 PMSGs is presented to evaluate and demonstrate the analysis conducted and the simple index proposed in the paper.

中文翻译：

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具有多个 PMSG 的弱并网风电场中由 PLL 确定的振荡稳定性的近似无模型评估

摘要 本研究调查了在具有多个永磁同步发电机 (PMSG) 的弱并网风电场中由锁相环 (PLL) 决定的振荡稳定性。为此，导出了风电场的等效模型。基于导出的等效模型，分析检查了由 PLL 动态确定的风电场振荡稳定性。本文解释了为什么风电场 PMSG 配备的 PLL 会在弱并网条件下导致不稳定风险。提出了一个简单的指标来近似评估由于锁相环引起的风电场不稳定风险。带有 PMSG 的风电场的参数模型对于计算建议的简单指标不是必需的。因此，它是无模型的，适用于难以建立参数化模型的实际应用。提供了一个具有 12 个 PMSG 的并网风电场的示例，以评估和演示所进行的分析以及本文提出的简单指标。