中文摘要：

电压暂降是电力系统不可避免的严重电能质量问题。总结电压暂降严重程度评价指标和评估方法；结合源、网、荷各侧电压暂降严重程度的影响因素、危害程度、特征与要求，分析暂降严重程度的内涵和评价测度存在条件，根据其不同层面的物理和数学特性，从多角度提出暂降严重程度评价的指标体系；以设备与过程电压暂降免疫力以及相关标准等为基础，归纳总结基于不确定性理论与不确定性测度的暂降严重程度评价思路和方法，并指出了值得深入研究的内容。

英文摘要：

Voltage sag is an inevitable serious problem in power system. This paper gave an overview of voltage sag severity, including its evaluation index and method. With the influencing factors, damage degree, the characteristics and requirements of severity in the power source-network-load sides, intension and evaluation measure existence conditions of sag severity were analyzed. According to the physical and mathematical properties of its different levels, the evaluation index system of voltage sag severity from multi-angle was presented. From current related standards about equipment and process voltage sag immunity, this paper made summarization on the thought and method of severity research based on uncertainty theory and uncertainty measure, for the purpose of pointing out worthy study in the future.