Sensitive Equipment Failure Assessment Caused by Voltage Sags Using Interval Probability

It is difficult to assess the impact of voltage sags on sensitive equipment because of the complex uncertainties involved in voltage tolerance capability. Determining the distribution regularity of voltage tolerance capability is an important step in voltage sag sensitivity assessment. Computers' voltage tolerance capability are obtained through laboratory tests. The point-value distribution function of voltage tolerance capability is calculated by Maximum Entropy Principle and then the interval probability distribution function is derived based on confidence interval, so as to derive an interval probability of equipment failure probability. The proposed model is finally verified in the IEEE-30 bus system. The results are compared with that of stochastic estimation method, showing that the proposed method can reflect actual conditions better and obtain accurate result.