Voltage Sag Sensitivity Evaluation of Industrial Process Based on Process Immunity Time and Maximum Entropy

On the basis of the existing sensitivity analysis of sensitive equipment to voltage sag, this paper evaluates the sensitivity of modern industrial process to voltage sag through process immunity time (PIT). Because PIT curve is affected by the amplitude and duration of voltage sag, and the PIT curve has uncertainty, a large number of samples are needed to accurately describe the random distribution law of the PIT curve, and it is greatly affected by subjective assumptions. In this paper, by dividing the voltage sag amplitude interval, the process interruption probability evaluation model based on duration severity index is established in each amplitude interval, and the probability density function of PIT curve in each amplitude interval is determined according to the maximum entropy principle (MEP), which can avoid the influence of subjective assumptions and accurately describe the random distribution law of PIT curve in the case of a small number of samples. Taking the air supply process as an example, the simulation results are compared with the existing evaluation methods. The results show that when the distribution law of PIT curve is unknown, the voltage sag sensitivity evaluation method proposed in this paper has accurate evaluation results, strong adaptability and no subjective assumptions.