A New Algorithm to Assess the Sensitive Equipment Fault Frequency Caused By Voltage Sag

In order to evaluate the frequency of sensitive equipment fault caused by voltage sag, the sensitive equipment fault frequency assessment method based on voltage tolerance curve (VTC) is established by considering the uncertainty of voltage sag tolerance of sensitive equipment, and overcoming the problem that the previous evaluation methods are overly dependent on hypothetical conditions, resulting in the lack of guarantee of the accuracy of the assessment results. According to the principle that the voltage sag energy is equal, the voltage sag normalization model is established to realize the three-phase normalization of non-rectangular or unbalanced sag, which overcomes the disadvantages of the previous evaluation method only applicable to the rectangular three-phase balanced sag. Based on the data of domestic research, the evaluation model proposed in this paper is verified by examples. The results show that the evaluation model proposed in this paper can better evaluate the number of voltage sag failures of sensitive equipment and prove the correctness of the proposed method.