A Calculation Framework for Quantifying the Probability of Ventricular Fibrillation of Rare Events

This paper outlines a novel method for calculating the probability that an individual exposed to an electrical hazard will experience ventricular fibrillation (v.f.) as a result. This method was developed to deal with high-impact low-likelihood (HILL) events where a minute percentage of the population is exposed to, or is susceptible to, the hazards created by the event. The consequences of a HILL event can be extreme, for example, death, but effective management of HILL events is a quandary for society since the likelihood of the extreme outcome is low. The framework presented here was developed to analyze and manage electrical hazards associated with ground potential rise during power system faults. It can, however, be applied to other events involving infrequent exposure of small percentages of the population to electrical hazards. Where electrical hazards occur as HILL events, the range of sensitivity in the population becomes critical so it is necessary to ensure that the more extreme individuals are explicitly considered. Most commonly used methods for estimating complex probabilities (for example, Monte-Carlo) are poorly suited to this application as they focus on the behavior of the “bulk” of probability distributions rather than characterizing the tails. The method outlined facilitates deliberate consideration of the complete range of sensitivities to electricity demonstrated by the human population. It also has the additional benefit of significantly reduced computational requirements while remaining intuitive in application. The validity of the method is confirmed by reproducing previous work investigating the probability of v.f. of step voltages using the safety criteria outlined in IEEE standard 80.