The study established that the application of graph theory enables the creation of a model of a country’s power system structure in the form of a tiered graph. This allows complex structural elements of the system, such as generating units, electrical substations, and power transmission lines, to be represented as nodes and edges in simulation models that can be used for analysis, dispatch control, and optimization of system operation. A simulation model of the unified power system has been developed to analyze operational efficiency and performance under various planned disturbance scenarios. To solve the given task, it is necessary to develop a model of the power system in the form of a tiered graph, where the nodes are generating equipment stations, transmission system substations with voltages from 330 kV to 750 kV, and distribution system substations with voltages from 110 kV to 220 kV, and the edges are power transmission lines with voltages from 110 kV to 750 kV. The model takes into account the generated and transmitted power, the nominal capacity and the number of transformers at the substations, the cross-section and maximum throughput of the power transmission lines, which made it possible to determine complex interconnections between its nodes and integrate the equipment into a unified power system for efficiency and performance analysis.

The research focuses on addressing the challenges of evaluating the effectiveness of modern power systems in countries with different configurations. Given the growing interest of con-sumers in the impact on the electricity supply schedule, the research is divided into two main parts. Firstly, a model has been developed to assess the operational efficiency of the power system. Secondly, a method for analyzing the efficiency of the energy system has been developed, based on a model of changes in energy system quality indicators. The presented model takes into account energy system characteristics such as the probability of network failure, normalized frequency of electricity, and the volume of consumed and supplied electrical energy. It is expected that this model will provide a more accurate assessment of the efficiency of the energy system under normal operating conditions. Additionally, a method for analyzing the operational efficiency of the energy system has been developed, based on a model of changes in energy system quality indicators. The uniqueness of this method lies in the introduction of a new comprehensive indicator of energy system efficiency, deter-mined by the convolution method of partial indicators, namely: the volume of electricity supply, supply quali-ty, and electricity supply efficiency. The reliability of the model is confirmed by calculations of the daily schedule of supply and load. Keywords: electric power system, electricity supply efficiency, evaluation of power supply system effi-ciency, electricity indicators, load schedule, consumer management, electricity supply quality.

The article investigates the economic feasibility of implementing eco-designed power transformers in the distribution electricity networks of Ukraine's Unified Energy System. Special attention is given to the analysis of energy losses during the operation of such transformers, which was carried out in accordance with the methodical recommendations of the Ministry of Energy and Coal Industry of Ukraine. Calculations were made for TMH-1000/10 type transformers in various operational modes, allowing for the assessment of their performance under real-world operating conditions. The economic benefits were evaluated using the net present value (NPV) method, which made it possible to compare the potential financial advantages of using eco-design with traditional transformer equipment options. The analysis showed that, despite the potential reduction in energy losses, the capital expenditures for implementing eco-designed transformers are significantly higher compared to traditional models. As a result, under current economic conditions and tariff policies, their application in the distribution networks of the Distribution System Operator does not provide sufficient economic benefit. The obtained results may be useful for energy companies, regulatory authorities, and researchers when making decisions regarding the modernization of the electric power infrastructure. The conclusions of the study could also serve as a foundation for further scientific work aimed at optimizing the parameters of power transformers, taking into account both energy and financial indicators. Keywords: Power Transformers, Distribution System Operator, Electrical Grid, Operation, Operation of Eco-Designed Transformers, Net Present Value (NPV).

Information and simulation models are important tools in the modern world for analyzing, designing, and optimizing various systems. One effective approach to their construction is the use of graph theory. In this article, we will examine the fundamental principles of constructing an information model using graphs and the method for analyzing the operability of this model under non-projected disturbances. In amidst increasing demands for reliability in the energy sector, the concept of developing an energy system in the form of a layered graph is becoming increasingly relevant and promising. A layered graph simulation model can provide an effective tool for optimizing energy supply and ensuring the stability and reliability of the system. Using a layered graph, it is possible to visualize the hierarchy of different energy sources, including renewable sources, traditional fuel types, and energy-efficient technologies. This will facilitate understanding the interaction between various components of the system and allow for the improvement of their integration. Keywords: electric power system, operability of the electric power system, assessment of the operability of the power supply system, non-project disturbances in the electric power system, generation, transformer substations, electricity consumers.