Type-4 wind is claimed to be immune from subsynchronous resonances (SSRs) that have been experienced by Type-3 wind with radial connection to series compensated lines. In this paper, we examine this claim through simplified analytical model building, analysis based on linearized models, and validation against electromagnetic transient (EMT) testbeds with full details. Two analytical models of Type-4 wind farm with radial connection to a series compensated line are built in $dq$-frames. The main difference of the two models is in grid-side converter (GSC)'s control mode, with one model assuming real power control and the other assuming dc-link voltage control. Relying on the analytical models, an efficient approach is demonstrated to obtain frequency-domain impedance models. Small-signal analysis is carried out using eigenvalue analysis and frequency-domain impedance model-based analysis. Potential stability risk is demonstrated, which is due to interaction of a mode associated to voltage source converter (VSC) in weak grid (termed as “weak grid mode”) and a mode associated to network LC resonance. The weak grid mode is influenced by grid strength and VSC control parameters, including phase-locked-loop (PLL) parameters. The small-signal analysis results are validated against two EMT testbeds with full details in MATLAB/SimPowerSystems and PSCAD/EMTDC, respectively.

中文翻译：

---

串联补偿网络中4类风的小信号稳定性分析

4 类风据称不受次同步谐振 (SSR) 的影响，而 3 类风在径向连接到串联补偿线路时会遇到次同步谐振 (SSR)。在本文中，我们通过简化的分析模型构建、基于线性化模型的分析以及针对电磁瞬态 (EMT) 测试台的完整细节验证来检验这一主张。径向连接到串联补偿线路的 4 类风电场的两个分析模型建立在 $dq$-frames 中。两种模型的主要区别在于网侧变流器 (GSC) 的控制模式，一种模型承担有功功率控制，另一种承担直流母线电压控制。依靠分析模型，展示了一种获得频域阻抗模型的有效方法。使用特征值分析和基于频域阻抗模型的分析进行小信号分析。潜在的稳定性风险得到了证明，这是由于弱电网中与电压源换流器 (VSC) 相关的模式（称为“弱电网模式”）和与网络 LC 谐振相关的模式的相互作用。弱电网模式受电网强度和 VSC 控制参数的影响，包括锁相环 (PLL) 参数。小信号分析结果分别在 MATLAB/SimPowerSystems 和 PSCAD/EMTDC 中针对两个 EMT 测试台进行了验证。弱电网模式受电网强度和 VSC 控制参数的影响，包括锁相环 (PLL) 参数。小信号分析结果分别在 MATLAB/SimPowerSystems 和 PSCAD/EMTDC 中针对两个 EMT 测试台进行了验证。弱电网模式受电网强度和 VSC 控制参数的影响，包括锁相环 (PLL) 参数。小信号分析结果分别在 MATLAB/SimPowerSystems 和 PSCAD/EMTDC 中针对两个 EMT 测试台进行了验证。