Multi-uncertainty Assessment for Failure Level of Sensitive Equipment Caused by Voltage Sag

The greatest difficulty for the evaluation of sensitive equipment failure level caused by voltage sag lies in the uncertainties of influencing factors and the method of modeling assessment. In order to evaluate the failure probability of equipment caused by voltage sag, the uncertain properties of voltage sag severity, voltage tolerance of equipment and the running state of equipment were studied based on the uncertainty of intension and extension. The uncertain models of influencing factors were established. The evaluation model for failure probability of equipment was established and its algorithms and assessment process were studied,using the determination principle of fuzzy membership function of the fuzzy safety event and the probability computation model of the fuzzy event. This method considers the multi-uncertainty of influencing factors of equipment failure level caused by voltage sag at the same time. Simulation studies have been carried out in the personal computer. The results show this method is correct and viable, and it can be conveniently applied in other related areas, not demanding any expert experience or subjective hypotheses.