Determination of the probability of failures in the operation of elements of urban heat supply systems in extreme operating conditions

Abstract

Modern centralized city or district heating systems of multi-apartment residential buildings, as well as administrative and industrial buildings, have a rather complex infrastructure. The main elements are heat generation systems, transport systems, and, accordingly, consumer subscriber inputs. The complexity of the system, which is determined by the necessary vital activity of many elements, affects the reliability of the heat supply infrastructure as a whole. The paper identifies the main reasons for the extreme operating conditions of heat supply systems in Eastern Europe and in present-day Ukraine. The main problems of operating systems during martial law are presented, including: damage to infrastructure due to hostilities, interruptions in the supply of fuel, water and electricity, difficulties in accessing repair work in the affected areas. The application of risk theory for complex systems in which the construction of a fault tree or event tree is widely used is justified. The advantage of the specified methods is the ability to determine the probability of failure or proper operation of the system as a whole with a known probability of failure of individual elements in extreme conditions. The paper considers the method of collecting and processing statistical data, as well as a rather promising universal method of expert assessments. For example, the probability of failure to connect a backup generator in the event of a shutdown or destruction of the main power supply system, the method of expert assessments was used for analysis. As a result of the study, the following were obtained: operating hours of power equipment in hours over years from commissioning; change in emergency shutdowns of the power unit over years. Analysis of the data provided indicates the presence of a period of increasing the reliability of power equipment as it is developed after commissioning, then, after some stabilization, an intensive decrease in reliability occurs, especially after the estimated resource is exhausted. The obtained pattern is characteristic of most technical systems.