Protection of the 110 kV power transmission line «Rudky - Sambir» based on the REL 670 digital terminal
Students Name: Malyniak Nazar Mykhailovych
Qualification Level: magister
Speciality: Electric Power Generation and Distribution Management Systems
Institute: Institute of Power Engineering and Control Systems
Mode of Study: full
Academic Year: 2022-2023 н.р.
Language of Defence: ukrainian
Abstract: Electricity is one of the most important branches of the state. It ensures the stable operation of all other branches of the state. In order for consumers to be able to use electricity stably, distribution system operators are obliged to reliably supply it to consumers. Reliability of power transmission, in such elements of the power grid as overhead lines, consists in reducing the number and time of shutdowns of this element. This can be achieved due to the following points: constant monitoring of equipment condition; availability and quality of means for carrying out repair works, including equipment modernization; use of fast-acting and reliable multi-stage equipment protection systems to reduce the time of destructive forces on the equipment during its damage or emergency modes. During the operation of overhead lines, various damages and emergency modes may occur, including short circuits, breaks and overloading of lines. The vast majority of all types of damage are short circuits. During the development of accidents, transitions of one type of damage to another are possible, or the occurrence of damage in other sections of the power grid, so it is necessary to turn off the damaged section of the network as soon as possible, for this, relay protection and automation devices are used [1]. 110 kV overhead lines can be protected by the following protections: Current: Maximum current protection; Current cut-off with time delay. Current cut-off without delay in time. Remote protection. The object of the study is the 110 kV Rudky-Sambir power transmission line. The subject of the study is the protection of the 110 kV Rudky-Sambir substation based on the REL670 digital terminal. The purpose of the study: selection and calculation of remote protection settings of the 110 kV "Rudky-Sambir" power transmission line based on the digital terminal of the ABB company, REL670. In this master’s thesis, the analysis and calculation of remote protection of the 110 kV "Rudkt-Sambir" substation was carried out. Digital remote protection based on the REL670 digital terminal was chosen. The REL670 digital terminal is a product of the ABB company [2]. In the energy system of Ukraine, relay protection and automation devices of this company are popular and widely used to protect various elements of the power grid and various voltage classes. They are characterized by versatility, high reliability and speed, this applies to both hardware and software. A feature of REL670 is the application of the principle of full-circuit measurement by each stage in parallel with respect to others, that is, each stage processes all six circuits of interphase AB, BC, CA and single-phase AN, BN, CN in parallel, and works simultaneously with six starting bodies. This principle of operation allows to reduce the protection activation time and increase its reliability. The terminal provides 5 levels of remote protection, but based on the configuration of the selected network section, we calculated 3 levels of protection (I, II, III) [3]: The 1st degree protects 85% of lines. The II stage protects the end of the power transmission line, and the I stage backs up. The activation time is increased by the degree of selectivity relative to the 1st stage. The III stage performs the role of close backup, that is, it reserves the I and II stages, and the operation time is increased by the degree of selectivity of one II stage. The characteristics of the activation zones of the corresponding stages were constructed in the impedance plane. During the operation of the protection, its false operation is possible in the following situations: the maximum load of the line, the oscillation mode in the power system, malfunctions in the voltage circuits. To avoid false tripping during the maximum load of the line, we calculated the parameters of the phase selector, which forms a "cut" on the characteristics of the protection stages and diverts it from the maximum load mode [4]. In order to prevent false triggering during the shaking mode, we have calculated the parameters of the blocking zones, provided that they cover all degrees of protection with a 10% margin. We also calculated the parameters of remote protection to block false triggering in the event of malfunctions in voltage circuits.