Generalized Estimation Method of Tripping Probability for Sensitive Equipment under Voltage Sags Based on Split H Blocks

The huge losses caused by voltage sag is getting worse, due to the increased usage of sophisticated equipment in the high-tech industry. To assess and mitigate against voltage sags, it is necessary of the availability of tripping probability information for sensitive equipment. This paper proposes a generalized estimation method of tripping probability for sensitive equipment under voltage sags based on split H blocks. Firstly, this paper proposes an identification method of the inflection point for voltage tolerance curve (VTC) based on an improved Freeman chain code, to identify more VTC shape information effectively, which overcome the lower accuracy issue associated with the traditional evaluation method owing to the availability of less VTC shape information. Secondly, a partitioning method is presented for uncertain regions of VTC, to solve the problem that the traditional method is only suitable for rectangular VTC, which increases the universality of equipment tripping probability assessment. Furthermore, this paper proposes a general evaluation method of tripping probability for sensitive equipment based on the proposed the optimal probability density functions and estimation method of its parameters, aiming to improve the accuracy of tripping probability of sensitive equipment under voltage sag. Finally, the accuracy and universality of the proposed method is verified, by data from the laboratory test and synthetic test.