Economic losses risk assessment of industrial users due to voltage sags based on uncertainty of process immunity

For accurate assessment of the financial losses of industrial customers caused by voltage sag, the paper presented a classification evaluation model based on the uncertainty of process immunity time in view of the existing assessment methods cannot effectively depict the characteristics of industrial processes and event severity. At first, the model introduced the concept of uncertainty of the process of immunity time based on process immunity time and uncertainty of equipment voltage tolerance, an out-of-limit parameter severity index was put forward and combined with the maximum entropy theory to determine the probability of the process parameter out of limit. On this basis, the paper established an industrial process fault tree analysis model. According to the features of immunity time of events at all levels, the consequences of sag event is divided into normal, sub-processes interruption and process interruption . The financial losses assessment was based on the three levels and the evaluation precision was effectively improved. Finally, through the analysis of the actual process, the results verify the correctness and feasibility of the method.