Uncovering patterns and distribution of severity indicators of empirical blackouts events

This paper deals with a time series of blackout events of the power transmission system in the Federation of Bosnia and Herzegovina (FB&H) in the period 2015–2024 and probability distributions that best fit these empirical data. The present study is focused on global behaviour and dynamics of time series ignoring the details of particular failures. We compiled the first blackouts database in FB&H including the relevant information on each blackout feature. The power law behaviour of the transmission network failure events in the FB&H power grid depending on their severity was identified. The results of this study show that the time intervals between the blackout events follow the exponential distribution. The data available from the FB&H power grid transmission centres in the observed period indicate that the frequency of all the blackout events in FB&H is not decreasing. It was determined that blackout probability increases substantially during the morning hours while the number of blackout events increases during the early summer and mid-fall months. However, the correlation analysis results show that there is only a weak, statistically insignificant correlation between event size and restoration time. The results of this study provide a set of unique and valuable insights to operators and decision makers for the safe operation of the FB&H power system. The broader scope of applications of the results obtained includes the connection of the FB&H power system to power distribution across the Balkans for transfers and trading. A dominant source of electricity in B&H is thermal power plant (about 65%) and it was of interest to perform an investigation into whether a dominant source of electricity impacts the blackout size distribution. It was demonstrated that the dominant type of electricity source does not have a significant effect on the alpha exponent of power law distribution.