The power supply system of the metal-cutting machines plant
Students Name: Beshlei Bohdan Mykhailovych
Qualification Level: magister
Speciality: Power Supply Systems and Energy Management
Institute: Institute of Power Engineering and Control Systems
Mode of Study: full
Academic Year: 2022-2023 н.р.
Language of Defence: ukrainian
Abstract: The demand for electrical energy is increasing more and more at enterprises. In order to solve the issues of technical improvement of production, it is envisaged to increase the level of electrification of production and efficient use of electricity. With a higher level of electrification of the enterprise, the need for additional capacities increases and a new, modern production power supply system is needed. The electrical system of electricity consumption is a complex of devices that serve to distribute and transmit electricity from the power source to the consumer. Basic principles of power supply system design: - consideration of all types of electrical loads with their location on the general plan; - provision of reliable power supply in compliance with all indicators of electricity quality and taking into account the categorization of consumers according to the reliability of electricity supply; - network design taking into account the perspective of the development of the design object, taking into account possible connections to the projected power sources of additional consumers; - the designed power supply system must be safe for service personnel, equipped with relay protection and automation devices to prevent the occurrence of emergency situations at the facility. In the master’s qualification work, the power source of the enterprise is the nodal substation of the power system, on which 2 autotransformers with a capacity of 125 MVA, each with voltages of 220/110/35 kV, are installed. The distance from the power system substation to the enterprise is 27 km. The time of using the maximum load of the plant is 4900 hours per year. The sections of the master’s qualification thesis are made on 97 pages of A4 format, which contain 39 tables, 13 figures and 17 sources of used literature. The graphic part contains 3 sheets made in A3 format and 1 sheet made in A1 format. The object of the study is the power supply system of the metal-cutting machine plant. The subject of the study is the choice of the optimal technical and economic option of the power supply system; The purpose of the study is to design the power supply system of the enterprise in accordance with current regulatory documents and using possible advanced technologies. Research results: In the "Electrical Loads" section, the estimated electrical loads for the repair and mechanical shop were determined separately using a modified statistical method, the estimated electrical loads of other workshops and the plant as a whole were calculated using the demand factor method. A cartogram of loads was also calculated. In the section "Choosing the scheme of external power supply", the selection of the voltage of the external power supply system of the enterprise was carried out, the selection of the optimal cross-section was carried out, and the number and power of the transformers of the main step-down substation were selected. In the section "Choosing an external power supply scheme", the number and power of workshop transformer substations and compensating reactive power units were determined, the cross-sections of the current-conducting cores of the cable lines that feed the workshop transformer substations were selected, the optimal power supply scheme was determined by comparing the discounted costs of several implementation options. In the section "Established modes of operation of the EPS system", the calculation of the established modes of the electrical system of power consumption was carried out, the positions of the tap-changer of the transformers were selected, and the calculated values of the voltages on the substation buses were determined. In the section "Calculation of short-circuit currents in the plant’s EPS, selection of switching and measuring devices", short-circuit currents were calculated, switches, disconnectors, current and voltage transformers for the power supply system were selected based on the calculated currents. In the next two sections, the settings for relay protection and automation devices are defined, recommendations for energy-saving and safe operation of the system are described. A general plan of the enterprise with a cartogram of electrical loads and routes of laying cable lines, a diagram of electrical connections of the electrotechnical system of power consumption, a structural implementation of the main step-down substation (plan and section) and a schematic diagram of connections of digital relay protection devices was also built. As a result of the work, the power supply system of the metal-cutting machine plant was developed, which is reliable and economically justified and provides consumers with high-quality electricity in full accordance with the requirements of current legislation.