This paper proposes a novel admittance model for the stability analysis of grid-connected voltage-source converters (VSCs) which features a symmetric structure. On this basis, the grid-connected VSC system can be represented by a reciprocal two-port circuit to explore the oscillation mechanism of the system. Furthermore, the grid-connected VSC system can be modelled as a single-input single-output (SISO) system rather than a multi-input multi-output (MIMO) system. We analytically evaluate the influences of the VSC control parameters and the power factor on the stability of the grid-connected VSC by employing the Nyquist criterion and the stability margin. In addition, we demonstrate that the VSC's current output is in inverse proportion to the system's gain margin. Further, an analytical expression of the current limit constrained by small-signal stability is derived in closed form so as to calculate the admissible current output. All of analysis results are verified by simulations based on Simulink and hardware-in-the-loop (HIL) platform.

中文翻译：

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并网变流器稳定性分析的对称导纳建模

本文提出了一种新颖的导纳模型，用于具有对称结构的并网电压源换流器 (VSC) 的稳定性分析。在此基础上，并网VSC系统可以用互易的二端口电路来表示，探索系统的振荡机理。此外，并网 VSC 系统可以建模为单输入单输出 (SISO) 系统而不是多输入多输出 (MIMO) 系统。我们通过使用奈奎斯特准则和稳定裕度分析评估了 VSC 控制参数和功率因数对并网 VSC 稳定性的影响。此外，我们证明了 VSC 的电流输出与系统的增益裕度成反比。更多，以闭合形式推导出小信号稳定性约束的电流限制的解析表达式，以计算允许的电流输出。所有分析结果均通过基于 Simulink 和硬件在环 (HIL) 平台的仿真验证。