基于EMT与RMS模型的频率扫描对比评估
Comparative Assessment of Frequency Scans using EMT and RMS Models
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中文总结 AI 辅助
本文对比Simulink中EMT与RMS模型对含同步发电机及两类逆变器的电力系统的频率扫描结果，明确RMS模型适用频段，分析不同逆变器的RMS表征难度及改进方法，关联系统阻抗奇异值与振荡特性。
中文摘要 AI 辅助
逆变器与电网阻抗的频率扫描对评估逆变器主导电力系统的小信号稳定性和系统强度至关重要。本文采用Simulink中的完全dq电磁暂态（EMT）模型和均方根（RMS）模型，对比了包含同步发电机、网侧跟随型逆变器及网侧形成型逆变器在内的多台发电机组的频率扫描结果，所有扫描均在相同设备额定值与运行工况下开展。频率扫描与时域仿真表明，RMS模型仅在低频段有效；研究发现，电流控制型网侧形成型逆变器比电压控制型网侧形成型逆变器更难用RMS模型表征，而引入内部电压控制环路可提升RMS表征的准确性。本文还探究了发电机与电网阻抗对接入点总系统阻抗的影响，并将系统的振荡模式与零点分别对应到系统阻抗第一、第二奇异值的峰值与谷值。
英文摘要
Frequency scans of inverter and grid impedances are crucial for assessing small-signal stability and system strength in inverter-dominated power systems. This paper compares frequency-scan results for several generating units, including a synchronous generator, grid-following, and grid-forming inverters, using fully dq electromagnetic transient and root-mean-square (RMS) models in Simulink. The scans are performed for the same device rating and operating point. Frequency scans and time-domain simulations show that the RMS models are valid only at low frequencies. We find that the current-controlled grid-forming inverter is more difficult to represent in RMS than the voltage-controlled grid-forming inverter. However, including the inner voltage-control loops improves the accuracy of the RMS representation. The paper also investigates the influence of generator and grid impedance on the total system impedance seen from the point of common coupling and relates the oscillatory modes and zeros of the system to peaks and dips in the first and second singular values of the system impedance, respectively.
