基于当量随机变量的设备电压暂降敏感度评估

Assessment on Equipment Sensitivity to Voltage Sags Based on Equivalent Random Variables

针对敏感设备电压暂降敏感度评估中,因同时包含随机变量和模糊变量而导致的设备故障事件的隶属函数确定困难和求解过程繁琐等问题,提出了基于当量随机变量的设备电压暂降敏感度评估方法。首先,分析了敏感设备耐受能力的模糊性。其次,引入当量随机变量的概念,将设备耐受能力的隶属函数变换为当量概率密度函数。再次,基于一次二阶矩方法,利用随机变量的均值和方差建立了评估模型。最后,分别以个人计算机、可编程逻辑控制器和交流调速器为例进行仿真,结果证实了所提评估方法的有效性。

Considering the problems such as the difficulty in determining the membership function of equipment failure events and the cumbersome solution process caused by both the random and fuzzy variables in the assessment on equipment sensitivity to voltage sags,an assessment method for the equipment sensitivity to voltage sags is proposed,which is based on equivalent random variables.First,the fuzziness of the tolerance capacity of sensitive equipment is analyzed.Second,the concept of equivalent random variable is introduced to transform the membership function of equipment tolerance capacity into the equivalent probability density function.Third,based on the first-order second moment method,an assessment model is established using the mean and variance of random variables.Finally,the effectiveness of the proposed assessment method is verified by the simulation results of examples including a personal computer,a programmable logic controller and an AC adjustable speed drive.