Abstract
One of the possible minimum short-circuit modes in the conditions of the high-voltage terminals of the power transformer of the step-down substation is the breakage of the busbar phase of the switchgear and its short-circuit to the ground from the transformer side. This mode combines two types of asymmetry – longitudinal and transverse, and its calculation and analysis are more convenient to perform using specialized software. In the conditions of power supply systems of industrial enterprises, such a calculation is further complicated by the presence of several nodes of the power supply system connection to the grid, the presence of own power plants, high density of load, and the prevalence of open sections of the 110-220 kV network over closed ones. The paper describes an algorithm for calculating a complex non-symmetrical mode, which is implemented in the software and computational complex "KATRAN" and is based on a combination of methods of sequential equivalent calculation for the steady-state mode and the method of symmetrical components for the calculation of the emergency non-symmetry mode. The module of automated calculation of protection settings of this software package has been used in the paper to assess the sensitivity of the transformer differential protection in the conditions of a two-phase short-circuit mode behind the transformer and a complex asymmetry mode. The described setting calculation module allows, based on the information about the parameters of the steady-state and emergency modes, as well as the characteristics of the measuring transformers, to calculate the settings of the protections in accordance with the requirements for protections and the recommendations of the manufacturers of microprocessor-based protection devices. The calculations performed made it possible to establish for which step-down substations it is necessary to perform a check of the sensitivity of the protections under the conditions of a complex asymmetry mode.
Keywords
relay protection, complex asymmetrical mode, short circuit, transformer protection, differential protection, sensitivity
1. Ershov Yu.A., Maleev A.V. Programmable model of trans-former differential protection in the MATLAB visual modeling environment. Izvestiya vysshikh uchebnykh zavedeniy. El-ektromekhanika [Bulletin of Higher Educational Institutions. Electromechanics], 2010, no. 3, pp. 64-68. (In Russian).
2. Ivanov V.A., Salmin A.G. Universal algorithm for digital equalization of shoulder currents for transformer differential protection. Materialy VII Mezhdunarodnoy nauchno-tekhnicheskoy konferentsii "Problemy i perspektivy razvitiya energetiki, elektrotekhniki i energoeffektivnosti" [Materials of the VII International Scientific and Technical Conference "Problems and Prospects of Energy, Electrical Engineering and Energy Efficiency"]. Cheboksary, Chuvash State University named after I.N. Ulyanov Publ., 2023, pp. 115-121. (In Russian)
3. Andreev M.V., Askarov A.B., Kiyevets A.V. Determination of settings for digital differential protection of a transformer using a mathematical model "power system-protection". Elektroenergetika glazami molodezhi: materialy XII Mezhdunar. nauch.-tekhn. konf. [Electric Power Engineering through the Eyes of Youth: Proceedings of the XII International Scientific and Technical Conference]. Nizhny Novgorod: NGTU im. R.E. Alekseeva Publ., 2022, vol. I, pp. 201-204. (In Russian)
4. Andreev M.V., Suvorov A.A., Rudnik V.E. Investigation of the functioning of differential protection of a transformer in an energy system with a wind power plant. Elektroenergetika glazami molodezhi - 2020: materialy XI Mezhdunarodnoy nauchno-tekhnicheskoy konferentsii [Elektroenergetika through the eyes of youth - 2020: materials of the XI International scientific and technical conference]. In 2 vols. Stavropol, North Caucasus Federal University, 2020, vol. 1, pp. 244-248. (In Russian)
5. Andreev M.V., Suvorov A.A., Kievetz A.V., Rudnik V.E. Use of a Mathematical Model for Setting up Digital Differential Protection of a Transformer. Vestnik Irkutskogo gosudarstvennogo tekhnicheskogo universiteta [Proceedings of Irkutsk State Technical University], 2020, vol. 24, no. 1(150), pp. 85-96. (In Russian). doi: 10.21285/1814-3520-2020-1-85-96
6. Kulikov A.L., Loskutov A.A., Bezdushny D.I. Improvement of Fault Mode Recognizability by Relay Protection Using Decision Tree Methods. Elektrichestvo [Elektrichestvo], 2023, no. 7, pp. 20-34. (In Russian). doi: 10.24160/0013-5380-2023-7-20-34
7. Igumentshev V.A., Malafeev A.V., Panova E.A., Varganova A.V., Gazizova O.V., Kondrashova Yu.N., Zinoviev V.V., Yuldasheva A.I., Krubtsova A.A., Anisimova N.A., Nasi-bullin A.T., Tremasov M.A., Shcherbakova V.S., Bogush V.K. Kompleks avtomatizirovannogo rezhimnogo analiza KATRAN 10.0 [Automated mode analysis complex KATRAN 10.0]. Computer program RF, no. 2019610251, 2019.
8. Igumentshchev V.A., Zaslavets B.I., Malafeev A.V., Bulanova O.V., Rotanova Yu.N. Modified Method of Sequential Equivalencing for Calculation of Modes of Complex Power Supply Systems. Promyshlennaya energetika [Industrial Power Engineering], 2008, no. 6, pp. 16-22. (In Russian).
9. Igumenshchev V.A., Malafeev A.V., Panova E.A. Raschet i analiz avariynykh nesimmetrichnykh rezhimov sistem el-ektrosnabzheniya [Calculation and analysis of emergency un-balanced modes of power supply systems]. Magnitogorsk, Nosov Magnitogorsk State Technical University Publ., 2013. 135 p. (In Russian)
10. Panova E.A., Voronkova V.E., Yarovikova E.P., Andreev S.M. Automated Calculation of Differential Protection Settings for Power Transformer at Step-Down Substation of Industrial Power Supply System. Elektrotekhnicheskie sistemy i kompleksy [Electrotechnical Systems and Complexes], 2026, no. 1(70), pp. 67-71. (In Russian). doi: 10.18503/2311-8318-2026-1(70)-67-71
Panova E.A., Yarovikova E.P., Voronkova V.E., Gavrikov M.I. Evaluation of the Sensitivity of Differential Protection of Power Transformers of Step-Down Substations in the Power Supply System of an Industrial Enterprise. Elektrotekhnicheskie sistemy i kompleksy [Electrotechnical Systems and Complexes], 2026, no. 2(71), pp. 49-53. (In Russian). https://doi.org/10.18503/2311-8318-2026-2(71)-49-53