Traditional power systems have been gradually shifting to power-electronic-based ones, with more power electronic devices (including converters) incorporated recently. Faced with much more complicated dynamics, it is a great challenge to uncover its physical mechanisms for system stability and/or instability (oscillation). In this paper, we first establish a nonlinear model of a multi-converter power system within the DC-link voltage timescale, from the first principle. Then, we obtain a linearized model with the associated characteristic matrix, whose eigenvalues determine the system stability, and finally get independent subsystems by using symmetry approximation conditions under the assumptions that all converters’ parameters and their susceptance to the infinite bus ($B_g$) are identical. Based on these mathematical analyses, we find that the whole system can be decomposed into several equivalent single-converter systems and its small-signal stability is solely determined by a simple converter system connected to an infinite bus under the same susceptance $B_g$. These results of large-scale multi-converter analysis help to understand the power-electronic-based power system dynamics, such as renewable energy integration. As well, they are expected to stimulate broad interests among researchers in the fields of network dynamics theory and applications.

中文翻译：

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具有对称性的多转换器馈电电网的小信号稳定性

传统电源系统已逐渐过渡到基于电力电子的系统，最近已合并了更多的电力电子设备（包括转换器）。面对更为复杂的动力学，要发现其物理稳定性的系统和/或不稳定（振荡）的物理机制是一个巨大的挑战。在本文中，我们首先从第一个原理开始，在直流母线电压时间范围内建立了一个多转换器电源系统的非线性模型。然后，我们获得带有相关特征矩阵的线性化模型，其特征值决定系统稳定性，并最终在假设所有转换器的参数及其对无限母线的敏感性的前提下，使用对称近似条件获得独立的子系统。${乙}_G$）相同。基于这些数学分析，我们发现整个系统可以分解为几个等效的单转换器系统，并且其小信号稳定性仅由在相同电纳下连接到无限总线的简单转换器系统确定。${乙}_G$。大规模多转换器分析的这些结果有助于了解基于电力电子的电力系统动力学，例如可再生能源集成。同样，它们有望激发网络动力学理论和应用领域研究人员的广泛兴趣。