Abstract
At different times, different devices were used as current sensors at electric power systems. However, the instrumental electromagnetic current transformers (CTs) proved more suitable and have been the most commonly adopted. The wide application of the CTs can also be justified by their reliability, subject to the operation rules. Accuracy and reliability of measured information sent from instrumental CTs are one of the important components for the correct operation of power system protection, data acquisition and telemetry systems, process control systems at electrical power facilities. There have been developed a lot of numerical methods for compensation of current transformer (CT) saturation. The article provides the comparison of several mathematical methods for secondary current restoration. The accuracy of different methods was analyzed under various conditions, namely, remaining flux, initial phase of short circuit current and noise presence. Linear combination of sine wave and aperiodic function was used as a test primary signal along with real short circuit current scope. Based on the performed analysis some recommendations and further development directions are stressed.
Keywords
Current transformers (CTs), distorted secondary current, magnetizing curve, compensated current, magnetizing current, unsaturated section.
1. Instruksiya po proverke transformatorov toka, ispolzuemyh v shemah relejnoj zashhity i izmerenija [Instruction for checking CT]. RD 153-34.0-35.301.2002. Moscow: ORGRJeS, 2003. 152 p. (In Russian)
2. Afanasyev V.V., Adonyev N.M., Kibel, V.M, Sirota I.M., Stognij B.S. Transformatory toka [Current transformers]. Leningrad, Energy, 1989, 416 p. (In Russian)
3. Saha M.M., Izykowski J., Lukowicz M., Rosolowski E. Application of ANN methods for instrument transformer correction in transmission line protection // Developments in Power System Protection, Conference Publication. IEE, 2001, no. 479, р. 303–306. DOI: 10.1049/cp:20010160.
4. Yu D.C., Cummins J.C., Wang Z., Hong-J.Y., Kojovic L.A., David S. Neural network for current transformer saturation correction // In Proc. IEEE Transmis. Distrib. Conf. New Or-leans, LA, 1999. P. 441–446. DOI: 10.1109/TDC.1999.755390.
5. Yu D.C., Cummins J.C., Wang Z., Hong-J.Y., Kojovic L.A. Correction of current transformer distorted secondary currents due to saturation using artificial neural networks // IEEE Trans. Power Deliv. 2001. Vol. 16, no. 2, р. 189–194. DOI: 10.1109/61.915481.
6. Khorashadi-Zadeh H., Sanaye-Pasand M. Correction of saturated current transformers secondary current using ANNs // IEEE Trans. Power Deliv. 2006. Vol. 21, no. 1, p. 73–79. DOI: 10.1109/TPWRD.2005.858799.
7. Baoming G., de Almeida A.T., Ferreira Fernando J. T.E. Estimation of primary current in saturated current transformer using flexible neural network // Trans. Inst. Meas. Control. 2006. Vol. 28, no. 1, p. 81–91. DOI: 10.1191/0142331206tm164oa.
8. Cummins J.C., Yu D.C., Kojovic L.A. Simplified artificial neural network structure with the current transformer saturation detector provides a good estimate of primary currents // the Power Eng. Soc. Sum. Meeting, Seattle. WA, USA, 2000. P. 1373–1378. DOI: 10.1109/PESS.2000.868725.
9. Erenturk K. ANFIS-based compensation algorithm for current-transformer saturation effects // IEEE Trans. Power Deliv. 2009. Vol. 24, no. 1, p. 195–201. DOI: 10.1109/TPWRD.2008.2005882.
10. Shi D.Y., Buse J., Wu Q.H., Jiang L. Fast compensation of current transformer saturation // IEEE PES Innov. Smart Grid Technol. Conf. Eur. ISGT Eur. 2010. P. 1–7. DOI: 10.1109/ISGTEUROPE.2010.5638931.
11. Shi D.Y., Buse J., Wu Q.H., Guo C. X. Current transformer saturation compensation based on a partial nonlinear model // Electr. Power Syst. Res. 2013. Vol. 97. P. 34–40. DOI: 10.1016/j.epsr.2012.11.019.
12. Hajipour E., Vakilian M., Sanaye-Pasand M. Current Trans-former Saturation Compensation for Transformer Differential Relays // IEEE Trans. Power Deliv. 2015. Vol. 30, no. 5, p. 2293–2302. DOI: 10.1109/TPWRD.2015.2411736.
13. Ziegler G. Digital Differential Protection. Belo Horizonte, 2005.
14. Protokol sovmestnogo zasedanija <...> po teme “Voprosy koordinacii raboty relejnoj zashhity i izmeritel'nyh TT” [Protocol of the joint meeting <…> on the theme of «The issues of coordination for relay system operation and instrumental CTs»] 2015, Available at: http://www.cigre.ru/research_commitets/ik_rus/b5_rus/materials/documents/%D0%A2%D0%A2%20%D0%B8%20%D0%A0%D0%97%D0%90_11.09.2015.pdf. (In Russian)
15. Korchanova A.S., Fedosov D.S. About changes in the CTs standards documentation for relay protection. IV Mezhdunarodnyj molodjozhnyj forum «Intellektualnye Energosistemy» [IV International Youth Forum "Intelligent Energy Systems"], 2016. Pp. 51–55. (In Russian)
16. Kuzhekov S.L., Degtyarev A.A., Doni N.A., Shurupov A.A., Petrov A.A., Koshelnikov I.A. Analysis Of Non-Selective Actions Of Busbar Differential Protection At External Single-Phase Short Circuits With Saturation Of Current Transformer In A Healthy Phase. Releynaya zashhita. Nauchno-prakticheskoe izdanie [Relay protection. Scientific and practical publication], 2019. P. 28–36. (In Russian)
17. Pazderin A.V., Murzin P.V., Odinaev I.N., Bobokalonov F.Z. Survey of data reliability in digital substation. Elektrotehnicheskie sistemy i kompleksy [Electrotechnical Systems and Complexes], 2019. Vol. 45, no. 4, p. 4–11. DOI: 10.18503/2311-8318-2019-4(45)-4-11. (In Russian)
18. Bekir K., Vehbi Olgac A. Performance Analysis of Various Activation Functions in Generalized MLP Architectures of Neural Networks // Int. J. Artif. Intell. Expert Syst. 2011. Vol. 1, no. 4, p. 111–122.
19. Parhomenko S. S., Ledenjova T. M. Neural networks training by Levenberg-Marquardt during data bulk condition. Vestnik VGU, Seriya: Sistemnyj analiz i informatsionnye tehnologii [Proceedings of Voronezh State University. Series: System analyses and Information Technology], 2014, vol. 2, pp. 98–106. (in Russian)
20. Kang Y.C. et al. Compensation of the distortion in the secondary current caused by saturation and remanence in a CT // IEEE Trans. Power Deliv. 2004. Vol. 19, no. 4, pр. 1642–1649. DOI: 10.1109/TPWRD.2004.835266.
21. Petelin S. Single phase CT model with saturation. Tsifrovaya podstantsiya [Digital substation], Available at: http://digitalsubstation.com/blog/2017/05/29/model-odnofaznogo-transformatora-toka-s-nasyshheniem/ (accessed 5 November 2019). (In Russian)
22. Korolev E.P., Liberzon Je.M. Raschet dopustimyh nagruzok v tokovyh tsepyah relenoy zashhity [Calculation load ability in the current circuits for protection] Мoscow: Energy, 1980. 208 p. (In Russian)