Operating conditions of a 5 MW cogeneration power plant within PrJSC «Lvivoblenergo»
Students Name: Syniavskyi Oleh Romanovych
Qualification Level: magister
Speciality: Electrical Energetics, Electrical Engineering and Electromechanics
Institute: Institute of Power Engineering and Control Systems
Mode of Study: full
Academic Year: 2025-2026 н.р.
Language of Defence: ukrainian
Abstract: The qualification work is devoted to a comprehensive study of the operating modes of medium-voltage electrical distribution networks (6–10 kV) using modern modeling software and assessing the impact of connecting cogeneration units (CGU) on the network performance. The relevance of the study is due to the growth of electrical loads, decentralization of generation, development of distributed energy sources and the need to increase the stability of energy supply in the conditions of post-war restoration of Ukraine’s infrastructure. Of particular importance are the issues of correct mode analysis, ensuring regulatory voltage levels, reducing losses and increasing the reliability of both main and distribution networks. The object of the study is an electrical distribution network of 6–10 kV, which includes overhead and cable lines, transformer substations and loads of various categories. The subject of the study is the operating modes of the 6–10 kV network in normal, post-accident and unevenly loaded conditions, redistribution of power flows, voltage levels, electricity losses and the impact on the network of connected local sources, in particular cogeneration units. The aim of the work is to increase the efficiency and reliability of the operation of 6–10 kV electrical networks by modeling their modes in the DAKAR software environment, assessing the impact on the CHP network, determining the optimal power supply structure and operating modes to reduce losses and ensure regulatory electricity parameters. The work analyzes the initial technical and topological data, forms a mathematical model of the distribution network taking into account the electrical parameters of lines, transformers and consumer load. Using the DAKAR software complex, steady-state modes are calculated at various characteristic points of the daily load schedule, including maximum and minimum load, and a number of post-accident modes are also simulated: disconnection of a bus section, outage of the supply line, transformer overload and asymmetric modes. A separate section is devoted to the inclusion of a cogeneration unit (CGU) in the network structure. The algorithm for its modeling, the features of operation modes in parallel with the network, the impact on voltage levels at the connection point and neighboring nodes, the impact on active and reactive power flows are considered. It is shown that a properly integrated CGU allows reducing the load on the supply lines, improving the voltage at the end sections of the network, ensuring a reduction in power losses and increasing the reliability of electricity supply to consumers. During the study, numerical results were obtained that cover the voltage values in the network nodes, current loads on lines and transformers, active and reactive losses. A comparative analysis of the modes before and after connecting the CGU was conducted. In minimum modes, it was found that the dominance of generation over load can lead to an increase in voltage, which requires adjusting the operation of transformer control devices. In maximum modes, it was established that the CGU can act as an effective source of peak load coverage, reducing the load on critical network elements. The results of the work showed that optimization of the operating modes of 6–10 kV networks is possible both on the basis of changing their topology (load redistribution, switching sections), and by modernizing the elements (increasing the cross-section of lines, choosing transformers with higher power, installing compensating devices). The connection of the KSU has confirmed its effectiveness as one of the tools for reducing losses and increasing the stability of the network, provided that the rules of parallel operation and proper organization of the control system are observed. The practical significance of the work lies in the possibility of using the obtained results in planning the reconstruction of 6–10 kV networks, forming the operating modes of district electric networks, optimizing the power supply schemes of industrial and municipal consumers, as well as in the feasibility study of introducing local sources of generation, in particular cogeneration plants.