中文摘要：

以构建用户友好的电网为目标，提出一种基于用户满意度区间特性的电力系统电压暂降频次解析式评估方法。利用故障线路长度与电压暂降幅值的解析式关系，通过迭代法直接求出临界故障点，以此确定系统内相关母线上的用户不满意区域。该方法综合考虑了用户满意度区间特性和用户设备在电压可接受不确定区域内的分布规律，根据确定的用户不满意区域评估用户接入母线的电压暂降频次。对5节点系统和IEEE-30节点标准测试系统进行仿真，并与传统故障点法进行比较，仿真结果证明，该方法能有效确定用户接入母线的电压暂降频次，适应于任意结构的系统。基于用户满意度区间特性评估得到的电压暂降频次更符合客观实际，具有一定理论价值和工程应用前景。

英文摘要：

On the goals of constructing a customer-friendly distribution system, a new analytical method considering the interval characteristic of customer satisfaction to assess the frequency of voltage sags is proposed. According to the analytical relationship between the length of the fault line and the voltage amplitude, the critical fault position is obtained directly by iterative algorithm and the unsatisfied area of network is determined. Considering the interval characteristic of customer satisfaction and combing the distributions of equipments in the uncertain region of the acceptable voltage, the frequency of voltage sags in the site of the buss is assessed by the determined unsatisfied area. The proposed method has been applied to both the five-buss system with the IEEE 30-bus reliability test system and compared with the fault position method. The results validate its correctness and practicality and it works for the analysis of any size networks. The assessment results based on the interval characteristic of customer satisfaction are more credible, and the new method is with academic value and practical foreground.