AI 中文总结
研究与电网形成变流器内部控制器相关的次同步振荡，通过基于连续的分岔分析揭示稳定性界限，聚焦强电网不稳定及极限环延续，还研究圆形电流限制器影响，发现弱电网虚假霍普夫分岔，强调GFM实施近似需谨慎。
AI 中文摘要
为确保电力系统的稳定性和安全性，理解与变流器接口发电机相关的复杂非线性电力系统动力学至关重要。例如，电网形成（GFM）变流器有望成为维持强大稳定电力系统的关键资产，但可能引发包括次同步振荡（SSO）在内的宽带稳定性问题，其潜在机制迄今未见或研究不足。本文详细介绍了基于连续的GFM变流器分岔分析，揭示了关于运行条件以及级联内部电压和电流控制器时间常数的稳定性界限。分析聚焦于由内部控制器相关的SSO导致的强电网不稳定，包括极限环越过霍普夫分岔点的延续，揭示了不可接受的大幅振荡的快速 onset。此外，研究了圆形电流限制器的影响，发现在采用平滑近似时，与上述SSO相关的弱电网中存在虚假霍普夫分岔；这表明至少在分岔研究中，GFM需要谨慎实施此类近似。
英文摘要
To ensure power system stability and security, it is vital to understand the complex nonlinear power system dynamics related to converter-interfaced generators. For example, grid-forming (GFM) converters are expected to be a key asset for maintaining a strong and stable power system, but might cause wide-bandwidth stability issues with underlying mechanisms heretofore unseen or understudied, including sub-synchronous oscillations (SSOs). This paper details a continuation-based bifurcation analysis of a GFM converter, revealing stability bounds with respect to operational conditions in addition to the time constant of the cascaded inner voltage and current controllers. We focus our analysis on the strong grid instability caused by an inner controller-related SSO, including continuation of the limit cycle past the Hopf bifurcation point, revealing rapid onset of unacceptably large oscillations. Furthermore, we investigate the impact of the circular current limiter, revealing spurious Hopf bifurcations in weak grids associated with the aforementioned SSO when adopting smooth approximations; this suggests the need for careful implementation of such approximations for GFMs, at least in bifurcation studies.
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