CC BY
17
kuNÎVERSlJM:
№ 10 (103)_ЛД ТЕХНИЧЕСКИЕ НАУКИ_октябрь. 2022 г.
ENERGY INDUSTRY
DOI -10.32743/UniTech.2022.103.10.143 73 SHORT CIRCUIT CHARACTERISTICS IN ELECTRICAL NETWORKS
Zuhriddin Hamidjonov
Assistant
of the Department of Electric Power Industry of the Fergana Polytechnic Institute, Republic of Uzbekistan, Fergana E-mail: z.xomidjonov@ferpi.uz
Ilyosbek Do 'ltayev
Master
of Fergana Polytechnic Institute, Republic of Uzbekistan, Fergana
ХАРАКТЕРИСТИКИ КОРОТКОГО ЗАМЫКАНИЯ В ЭЛЕКТРИЧЕСКИХ СЕТЯХ
Зухриддин Хамиджонов
ассистент кафедры электроэнергетики Ферганского политехнического института, Республика Узбекистан, г. Фергана
Илёсбек Доултаев
магистр
Ферганского политехнического института, Республика Узбекистан, г. Фергана
ABSTRACT
In this article, short circuits occurring in medium and low voltage distribution networks are studied. In it, the situation, effects and damages of short circuits in electrical networks are considered based on switching schemes.
АННОТАЦИЯ
В данной статье исследуются короткие замыкания, возникающие в распределительных сетях среднего и низкого напряжения. В ней рассматривается ситуация, последствия и повреждения коротких замыканий в электрических сетях на основе коммутационных схем.
Keywords: short-circuit, electrical networks, consumer, short-circuit performance characteristics. Ключевые слова: КЗ, электрические сети, потребитель, КЗ.
Short-circuit
In this case, the consumer resistance is short-circuited by a fault (by metal or by arcing) so that a very high line current flows. A distinction must be drawn between symmetrical (three-pole) and asymmetrical (one or two-pole) short circuits. Only the three-pole fault can be represented in the single-phase equivalent circuit diagram. That is why only this type of fault is examined in the following experiment. When a short-circuit occurs, the transmitted power is generally much greater than the thermal limit rating of the transmission line. The faulty condition must thus be recognized by the network protection device and switched off within the shortest possible time. In order to better understand these three
operating cases, they are to be graphically displayed in the form of a vector or phasor diagram. In general, vector diagrams are used for networks operated with sinusoidal voltages in order to better illustrate the processes.
The representation of an AC quantity as a vector makes two statements about this quantity: namely about the value (vector length) and the phase relation (vector direction). The sinusoidal curve of the quantity can be recorded as a projection of the rotating point of the vector on the ordinate of the coordinate system; the angular velocity © is equal to the circuit frequency 2nf of the oscillation. Expressed the other way round, a vector represents a snapshot of a sinusoidal phenomenon. Vectors
Библиографическое описание: Hamidjonov Z.M., Do'ltayev I. SHORT CIRCUIT CHARACTERISTICS IN ELECTRICAL NETWORKS // Universum: технические науки : электрон. научн. журн. 2022. 10(103). URL: https://7universum. com/ru/tech/archive/item/143 73
№ 10 (103)
A UNI
/m te;
UNIVERSUM:
ТЕХНИЧЕСКИЕ НАУКИ
октябрь, 2022 г.
can be geometrically added and subtracted, thus allowing, e.g., the voltage drops in a network to be easily illustrated. In this connection, the use of the complex calculations in which the vectors are shown in the Gaussian plane is favourable. By multiplication by the complex operator j, for example, a 90° rotation of a vector is achieved. However, complex representations are used here only when the relationships shown in the vector diagrams are to be evaluated mathematically. One vector is selected arbitrarily as the reference vector with the phase angle 0°. All other angles in the vector diagram are with reference
to this. For practical reasons, the voltage vector at the line end is selected as the reference vector when representing the operating performance of a transmission line.
The following illustrations show the single phase equivalent circuit diagram of a loss-free transmission line in the operating cases described above with the currents, voltages and voltage drops indicated; the respective combined voltage and current vector diagram is included. The following uniform indices are used for the representations:
Figure 1. Single-phase equivalent circuit diagram of a loss-free three-phase transmission line in no-load operation, with appropriate vector diagram
Beginning of line point 1 End of line point 2
Neutral point point 0
With regard to the experiment procedure, it must be mentioned that the relationships barely change when studying low-loss transmission lines, as the effective resistance R of the high and ultra-high voltage lines is equal to approximately 10% of the reactance X = œL in
the most un favourable case. Due to the geometric addition of the voltage drops, the mathematical treatment becomes much more complex, while the results deviate insignificantly from those determined through the study of a loss free transmission line. In order not to lose sight of what is important, the following derivations refer to the loss-free transmission line. Deviations in the performance of real, i.e. low-loss transmission lines are noted in the appropriate places.
№ 10 (103)
A UNI
/т те;
UNIVERSUM:
технические науки
октябрь, 2022 г.
Short-circuit performance characteristics
Figure 2. Single-phase equivalent circuit diagram of a loss-free three-phase transmission line with short-circuit
and coresponding vector diagram
In this type of operation, the transmission line is short-circuited at the end, i.e. I2 = I12 and U2 = 0. The current I1 at the beginning of the transmission line results from the geometric addition of the currents I10 through the operating capacitance Cb/2 at the beginning of the line and I12 through the line inductor. The phase
angle ©1 between U1 and I1 is exactly 90°; for low-loss transmission lines, it is still about 85°.
In the experiment procedure the three operating cases described above are simulated first. Afterwards the performance of the transmission line model is investigated for mixed ohmic-inductive and a mixed ohmic-capacitive load.
References:
1. Schlabbach J., & Schlabbach, J. (2005). Short-circuit currents (Vol. 51). Iet.
2. Hamidjonov Z.M (2022). Elektr energiyasini tejash usullari. НТЖ ФерПИ, 1(6), 184-186.
3. Hamidjonov Z.M (2022). Elektr uzatish liniyalarida quvvat o'tkazuvchanligini qobiliyatini oshirish usullari. НТЖ ФерПИ, 1(6), 64-69.
4. Hamidjonov.Z.M (2022). Yuqori kuchlanishli elektr uzatish liniyalarini elektr o'tkazuvchanlik qobiliyatini oshirish usullari. НТЖ ФерПИ, 2022, 1(1), 191-195.
5. Mirkamol R., & Zuriddin X. (2019). Увеличение эффективности турбогенераторов теплового электрического центра. Journal of Technical sciences, (3), 10-13.
6. Kh E.A., Hamidjonov Z.M., Rakhimov M.F., & Abdullaev A.A. (2019). Increasing efficiency of turbo generators in heat electric centers. European science, (6), 48.
7. Hamidjonov Z. (2021). Elements of power grid design. Uzbekistan Journal of Engineering and Technology.
8. Zuhriddin H., & Saida I. (2022). ELEKTR ENERGIYASINI TEJASH MASALALARI. Involta Scientific Journal, 1(7), 69-72.
9. Hamidjonov Zuhriddin (2021). ELEMENTS OF POWER GRID DESIGN. Universum: технические науки, (11-6 (92)), 91-93.
10. Зухриддин Маъруфжонугли Хамиджонов (2020). ЭЛЕКТР ТАРМО^ЛАРИНИ ЛОЙИХДЛАШ ЭЛЕМЕНТЛАРИ. Science and Education, 1 (9), 265-270.
11. Эралиев Абдинаби Хакимович, Хамиджонов Зухриддин Маръуфжон Угли, Рахимов Миркамол Фархотжон Угли, & Абдуллаев Абдувохид Абдугаппар Угли (2019). Повышение эффективности турбогенераторов в теп-лоэлектрических центрах. European science, (6 (48)), 37-40.
12. Hamidjonov Zuhriddin, Abdullaev Abduvokhid, Ashurov Abdulahad, & Ergashev Komiljon Ravshan O'G'Li (2021). REACTIVE POWER COMPENSATION IN POWER GRIDS. Universum: технические науки, (11 -6 (92)), 87-90.
№ 10 (103)
UNIVERSUM:
ТЕХНИЧЕСКИЕ НАУКИ
октябрь, 2022 г.
13. Hamidjonov Z.M (2022). O'zbekiston Respublikasida qayta tikanadigan energiya manbalaridan foydalanish istiq-bollari. НТЖ ФерПИ, 1(6), 112-116.
14. Farxodjon o'g'li R.M., & Zuriddin Ma'rufjon o'g X. (2019). ISSIQLIK ELEKTR MARKAZI TURBOGENERA-TORLARI SAMARADORLIGINI OSHIRISH. Техник тадкщотлар журнали, (4).
15. .Nabievna N.F., Valijonua A.A., & Abdulvosievna K.F. (2020). Efficiency of using information resources and technology in students research work. ACADEMICIA: An International Multidisciplinary Research Journal, 10,
16. Комолддинов Сохибжон Солиджон Угли, Кодиров Афзал Ахрор Угли, Ашуров Абдулахад Валижон Угли, & Тухтасинов Саидисломхон Хасанхон Угли (2022). РЕГУЛИРОВКА ИЗМЕНЕНИЯ НАПРЯЖЕНИЯ В УСТРОЙСТВЕ АВТОКОМПЕНСАЦИИ (НА ПРИМЕРЕ ОДНОЙ ФАЗЫ). Universum: технические науки, (5-9 (98)), 49-54.
17. Qodirov A.A., Ashurov A.V. (2022). Irrigatsiya nasoslarining energiya samaradorligini ashirishning innovatsion texnologiyalarini ishlab chiqish. FarPI Respublika ilmiy-texnika jurnali, 64-68.
18. Эргашев Комилжон Равшан Угли, Ашуров Абдулахад Валижон Угли, & Бойназаров Бекзод Бахтиёрович (2021). МЕТОДЫ РЕГУЛИРОВКИ НАПРЯЖЕНИЯ. Universum: технические науки, (11 -5 (92)), 58-62.
19. Ashurov A.V. (2020). Efficeincy of using information resources and technology in students' research work. ACADEMIKA An International Multidisciplinary Research Journal, (11), 1686-1689.
20. Ashurov A. V, Nasretdinova F. N, Qobilov M.X. (2022). Havo liniyalarida toj razryadining hosil bo'lishi va ularni bartaraf qilish usullarini tadqiq etish. FarPI Respublika ilmiy-texnika anjumani materiallari, 152-158.
21. Halilova F.A. Nasretdinova F.N. Ashurov A.V. (2021). Ta'limda o'quv faollikni oshirish omillari. ACADEMICIA: Xalqaro ko'p tarmoqli tadqiqot jurnali, 4(11), 1090-1094.
22. Kamoliddinov S.S., Qodirov A.A., Ashurov A.V., To'xtasinov S.X. (2022). Регулировка изменения напряжения в устройстве автокомпенсации (на рпимере одной фазы). UNIVERSUM Технические наука, 5(98).
23. Hamidjonov Z.M. (2021) ELEKTR ENERGETIKASI TA'MINOTI TIZIMI UZLUKSIZLIGINI TA'MINLASH DOLZARB MUAMMOLARINING SAMARADOR YECHIMLARI 1, 19-21.
24. Абдулхамидов А.А. Абдуллаев Абдувохид. Муминов Бобур Применение виртуальной лаборатории в учебной работе, 64-65.
25. Abdullaev A. (2020). ПЕРЕХОДНЫЕ ПРОЦЕССЫ НА ИСТОЧНИКАХ ПИТАНИЯ СВЕТОДИОДОВ И МЕТОДЫ ИХ УСТРАНЕНИЯ. Главный редактор: Ахметов Сайранбек Махсутович, д -р техн. наук; Заместитель главного редактора: Ахмеднабиев Расул Магомедович, канд. техн. наук; Члены редакционной коллегии, 44.
26. Исмоилов Иброхимжон Келдибоевич, & Турсунов Дониёр Абдусалимович (2020). ПРИМЕНЕНИЕ МЕТОДОВ РОБАСТНОГО УПРАВЛЕНИЯ В СИСТЕМАХ РЕГУЛИРОВАНИЯ СИНХРОННЫХ ГЕНЕРАТОРОВ. Universum: технические науки, (12-5 (81)), 28-31.
1680-1684.
