中文摘要：

随着新能源、无功补偿等电力电子设备的大量接入,交流系统相对变弱,分析电力电子多馈入电力系统潜在的失稳、精确度量交流系统电压支撑能力十分重要。文中首先推导了单馈入系统短路比与小干扰稳定性特征方程的显示关系式,建立了单馈入系统短路比与其小干扰稳定间的联系。其次,在一定假设条件下,证明了n馈入系统的动态可由n个独立的单馈入系统表征,从而实现多馈入系统稳定性向单馈入系统稳定性的解耦和简化。最后,提出可用于度量交流系统的强度的广义短路比概念（generalized short circuit ratio,g SCR）。所提出的广义短路比是一个与系统振荡频率无关的静态变量,但反应的是多馈入系统的小干扰稳定裕度,并且在单馈入和多馈入系统下可实现物理意义和数学形式的统一。仿真算例表明了g SCR定义的合理性和有效性。

英文摘要：

More and more renewable energy generators and var compensation devices are connected to AC power systems via power electronic devices, which makes the AC systems weaker and weaker, so it is important to exactly measure the strength of AC systems and analyze the potential stability problems of multiple power electronic based devices infeed systems（MPEIS）. Firstly, this paper deduced the explicit characteristic function of short circuit ratio（SCR） and analyzed the relationship between the SCR and small signal stability problem. Secondly, based on the ideal model of MPEIS, the dynamic characteristics of multi infeed system were represented by n independent single infeed systems, thus the multi-infeed system can be decomposed into several single infeed systems. Finally, a new concept named generalized short circuit ratio（g SCR） was proposed to analyze the small signal stability of multi infeed system, which can be used to depict the strength of AC systems and unify the concept of SCR in single and multi-infeed system physically and mathematically. The simulation results demonstrate the rationality and effectiveness of the defined g SCR.