Low-frequency oscillations have been observed in a real-world solar photovoltaic (PV) farm. The goal of this research is to build a simplified analytical model in the synchronous frame for large-signal simulation and small-signal analysis. The latter, e.g., eigenvalue analysis and participation factor analysis, can reveal influencing factors of the oscillations. Two simplified analytical models are proposed, ignoring PV dc-side dynamics (e.g., dc/dc boost converter control and maximum power point tracking), while preserving the grid-side converter (GSC) controls and electromagnetic dynamics of the grid interconnection. The first model assumes the input power from PV's dc side known and constant. The second model assumes that PV's dc side is represented by a constant dc voltage behind an impedance. The simplified models are compared with an electromagnetic transient (EMT) testbed with full details on time-domain simulation results, admittance frequency-domain responses, and eigenvalue-based stability analysis results. The second simplified model is found as capable of accurately predicting oscillation stability.

中文翻译：

---

用于低频振荡分析的并网太阳能光伏系统降阶分析模型

在真实世界的太阳能光伏 (PV) 农场中观察到低频振荡。本研究的目标是在同步框架中建立一个简化的分析模型，用于大信号仿真和小信号分析。后者，例如特征值分析和参与因子分析，可以揭示振荡的影响因素。提出了两种简化的分析模型，忽略光伏直流侧动态（例如，dc/dc 升压转换器控制和最大功率点跟踪），同时保留电网侧转换器 (GSC) 控制和电网互连的电磁动态。第一个模型假设来自 PV 直流侧的输入功率已知且恒定。第二个模型假设 PV 的直流侧由阻抗后面的恒定直流电压表示。将简化模型与电磁瞬态 (EMT) 测试台进行比较，其中包含有关时域仿真结果、导纳频域响应和基于特征值的稳定性分析结果的完整细节。发现第二个简化模型能够准确预测振荡稳定性。