Stochastic estimation trip frequency of sensitive equipment due to voltage sag

This paper presents a case study where the sensitivity of the sensitive equipment due to voltage sag is estimated using a stochastic estimating method based on voltage tolerance curve and load voltage sag sensitivity. The randomicity of the equipment voltage tolerance is described using the normal distribution probability density function. The trip frequencies of sensitive equipment are estimated using accumulative sum mode in order to avoid identifying sensitivity grade for different equipment types. The simulation results comparing with the practical testing show that the proposed method is corrective and effective.