Due to unfavorable factors, dangerous conditions occurred in the delivery of electric energy in Poland. This was the most serious incident of its kind since the 1980’s. Such a serious incident raised concern about the safety of the electric power system in the summer and led to the formulation of conclusions for the future. In this article, the author analyses the conditions, which caused that situation. Poland was experiencing a doubt in August 2015, which along with an extremely high maximum daily temperature created remarkably unfavorable conditions for power plants and decreased the capacity of overhead power lines. Such unfavorable metrological conditions occurred not only in Poland, but also in Central-Eastern and Western Europe. It is worth emphasizing that the safety of electric energy delivery was endangered only in Poland. The improper renovation and upkeep policies, as well as unplanned outages in power plants caused a significant decrease of available power in the National Electric Power System. Unscheduled flows between Germany and Poland ruled out the possibility of importing electric energy at such a critical time. The author presents the correlation between the maximum daily air temperature in the sweltering heat and an increase in the demand for electric energy. Overall, unfavorable conditions posed a threat in the delivery of electric energy in Poland. In this article, the author draws attention to the report from the Supreme Audit Office (Najwyższa Izba Kontroli – NIK) from 2014, which predicted such a dangerous situation. Unfortunately, that report remained unnoticed. The author formulated appropriate solutions in order to increase the safety of electric energy delivery in the summer and to prevent such occurrences in the future.
The paper concerns the assessment of blackout hazards in the power systems. On the basis of statistical data from more than one hundred failures in power systems that affected the world in the last fifty years, the analysis was carried out regarding the number of people affected by a blackout, power losses in the system, duration of a failure and its direct causes. The paper also describes the methodology of risk analysis and vulnerability analysis of the extraordinary events occurrence in electrical power systems resulting in failures. The structure of risk analysis was based on the bow tie model, identifying threats, unwanted events, barriers and consequences of a system failure. Moreover, particular attention was drawn to the impact of the power reserve deficit in the Polish Power System in the coming years on the increase in the risk of a blackout failure.