Evaluation Method for Tripping Probability of Sensitive Equipment Under Voltage Sag Based on Energy Loss Diagram

The evaluation of the tripping probability of sensitive equipment (SE) under voltage sags is the key prerequisite for voltage sag mitigation. The traditional method of evaluating the tripping probability of SE poses two challenges, including the difficulty of accurate estimation under nonrectangular voltage sags and contradiction between the higher data dependency of traditional methods and the less historical data in practice. The voltage sag energy loss index, which contains waveform change information, is a feasible tool to address these challenges. This study proposes a method based on the energy loss diagram (ELD) to characterize the tolerance of SE. First, the energy loss characteristics and ELD is established as a basis for estimating the tripping probability, solving the difficulty of accurate estimation for the SE tripping probability under nonrectangular voltage sags. Second, an evaluation method for ELD parameters based on the hidden Markov model (HMM) is proposed to solve the problem of high data dependence. Third, an estimation method of annual tripping frequency for SE is proposed, which can provide the foundation for voltage sag mitigation configuration. Finally, two case studies, including the evaluation based on testing and evaluation based on field data of a manufacturer, demonstrate the effectiveness of the proposed method. The research offers a more reliable basis for testing and evaluating SE tolerance and formulating effective mitigation strategies.