Study of mode recognition in 10 kV cable networks for organizing protection against single-phase ground faults

Relevance. Distribution networks account for the largest share of Russia's power grid. The most common fault type in these networks is a single-phase ground fault. Selective identification of the faulty cable line can prevent its escalation into a three-phase fault, improving power supply reliability.

Purpose. A multiparameter method of ground fault protection uses several electrical quantities to determine the network mode. This method makes the protection selective and more sensitive. Different electrical quantities are of different value for the mode recognition task. The goal of the research is to study the parameters of current and voltage that are used for relay protection. Investigation of the ability to recognize network mode based on this parameters.

Methods. We obtained statistics by using simulation modeling of the cable network in the Matlab software package in the Simulink expansion package in all possible modes. And then we used discrete Fourier transform of the full period to obtain filtred harmonics and quadrature components of the values of zero-sequence currents and voltages.

Results. The article describes the block and functional diagrams of measuring elements that uses the dependencies of electrical quantities are proposed. The article determines the areas formed by electrical quantities on the graph in different modes such as internal and external steady-state single-phase ground faults and arc intermittent single-phase ground faults. The graph consists of the dependence of two electrical quantities. It was also revealed that the areas of different modes have mutual intersections.

Conclusions. The results of the study are suitable for the implementation of multiparameter protection.

1. Fedotov A.I., Akhmetvaleeva L.V., Basyrov R.S., et al. Rating of amplitudes of high harmonics in determining feeder with single-phase ground fault. Power engineering: research, equipment, technology. 2020; 22(1): 58-68. (In Russ.) doi.org/10.30724/1998-9903-2020-22-1-58-68

2. Fedotov A.I., Vagapov G.V., Abdullazyanov A.F., et al. Digital power lines faults monitoring system. Power engineering: research, equipment, technology. 2021; 23(1):146-155. (In Russ.) https://doi.org/10.30724/1998-9903-2021-23-1-146-155

3. Achitaev A.A., Suslov K.V., Volkova I.O., et al. Development of an algorithm for identifying single-phase ground fault conditions in cable and overhead lines in the networks with isolated neutral. Energy Reports. 2023; 9:1079-1086. doi:10.1016/j.egyr.2023.01.046

4. Toader D., Solea C., Vesa D., et al. Analysis of the possibilities of selective detection of a single line-to-ground fault in a medium voltage network with isolated neutral. Energies. 2021;14(21):7019. doi:10.3390/en14217019

5. Kachesov V., Lebedev A., Kitova E. Monitoring in 6–35 kV power networks, location of singlephase ground fault and detection of fault feeder. International Journal of Electrical Power & Energy Systems. 2023;152:109271-109271. doi:10.1016/j.ijepes.2023.109271

6. Shuin V.A., Gusenkov A.V. Zashchity ot zamykanii na zemlyu v elektricheskikh setyakh 6–10 kV. Moscow: NTF «Energoprogress», 2001. (In Russ).

7. Borukhman, V.A. Ob ekspluatatsii selektivnykh zashchit ot zamykanii na zemlyu v setyakh 6-10 kV i meropriyatiyakh po ikh sovershenstvovaniyu. Energetik. 2000; 1:20–22. (In Russ).

8. Andreev, V.A. Releinaya zashchita i avtomatika sistem elektrosnabzheniya. Moscow: Vysshaya shkola, 2006. (In Russ).

9. Shuin V.A., Vorobyova E.A., Dobryagina O.A., et al. A way to increase the operating efficiency of admittance earth fault protection in 6–10 kV cable networks with isolated neutral. Vestnik IGEU. 2018;4:20–22. (In Russ). doi: 10.17588/2072-2672.2018.4.020-030

10. Shuin V.A. Nachal'nye fazovye sootnosheniya elektricheskikh velichin perekhodnogo protsessa pri zamykaniyakh na zemlyu v kabel'nykh setyakh 6-10 kV. Elektrichestvo. 1991;10:58-61.

11. Shuin V.A., Kutumov Yu.D., Kuzmina N.V., et al. Simulation study of 6–10 kV cable lines for transient processes calculation during earth faults. Vestnik IGEU. 2021; 5:30-40. doi: 10.17588/2072-2672.2021.5.030-040

12. Vorobyova E.A., Shuin V.A. Analiz dostovernosti ekvivalentnykh modelei kabel'nykh setei 6-10 kV dlya rascheta perekhodnykh protsessov pri odnofaznykh zamykaniyakh na zemlyu. In: Mezhdunarodnyi nauchno-tekhnicheskaya konferentsiya: (XVIII Benardosovskie chteniya); 27–29 May 2015; Ivanovo, Russia. Ivanovo Publ., 2015. pp. 456–460. (In Russ).

13. Vorobyova E.A., Shuin V.A. Otsenka tochnosti ekvivalentnykh modelei kabel'nykh setei 6-10 kV dlya rascheta perekhodnykh protsessov pri odnofaznykh zamykaniyakh na zemlyu In: VI mezhdunarodno nauchnaya-tekhnicheskaya konferentsiya. Tom 2; 09–13 Nov 2015; Ivanovo, Russia. Ivanovo Publ., 2015. pp. 63–66. (In Russ).

14. Maksimova M.N., Antonov V.I., Soldatov A.V., et al. Сonversion of intermittent arc fault currents to information signals for phase-to-ground fault protection. Power Technology and Engineering. 2022;56(2):290-294. doi: 10.1007/s10749-023-01508-w

15. Kuliński K., Heyduk A. Ground fault in medium-voltage power networks with an isolated neutral point: spectral and wavelet analysis of selected cases in an example industrial network modeled in the atp-emtp package. Energies. 2024;17(7):1532. doi:10.3390/en17071532

16. Kulikov A.L., Misrikhanov M.Sh. Vvedenie v metody tsifrovoi releinoi zashchity vysokovoltnykh LEP. Moscow: NTF «Energoatomizdat», 2007. (In Russ).