Earth fault protection for compensated electric networks based on frequency filters

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Authors:

V.F.Syvokobylenko, Dr. Sc. (Tech.), Prof., orcid.org/0000-0002-7720-0540, Donetsk National Technical University, Pokrovsk, Donetsk Oblast, Ukraine, e-mail: This email address is being protected from spambots. You need JavaScript enabled to view it.; This email address is being protected from spambots. You need JavaScript enabled to view it.

V.A.Lysenko, Cand. Sc. (Tech.), orcid.org/0000-0002-6411-3114, Donetsk National Technical University, Pokrovsk, Donetsk Oblast, Ukraine, e-mail: This email address is being protected from spambots. You need JavaScript enabled to view it.; This email address is being protected from spambots. You need JavaScript enabled to view it.

Naukovyi Visnyk Natsionalnoho Hirnychoho Universytetu. 2020, (1):69-74
https://doi.org/10.33271/nvngu/2020-1/069

 повний текст / full article



Abstract:

Purpose. Development of selective microprocessing earth fault protection in compensated electrical networks of 6‒35 kV. Use of the Goertzel algorithm for the separation of components of frequencies higher than fundamental frequency from the zero sequence voltage and currents.

Methodology. The methods of mathematical modeling and analysis of transients in compensated electric networks of 6‒35 kV, Fourier transform and Goertzel algorithm, construction of earth-fault protection algorithms, and experimental research are used.

Findings. The results of mathematical modeling show that in compensated electric networks of 6‒35 kV at phase-to-ground fault the reactive power direction in a in a damaged feeder1can be similar to the one in an undamaged feeder1; therefore, conventional protections cannot perform selective operation. This action can be provided by protections based on separation of components of fixed frequencies of 200‒300 Hz from the zero sequence voltage and currents. Their reactive power in an undamaged connection is always directed off tyres, because is hardly compensated by the reactor regardless of degree of its cavity tuning. When applying band-pass frequency filters, the required protection responsivity is not always provided at phase-to-ground fault through resistances exceeding 10‒15 Ohm. Moreover, failure of steady operation of filters is possible due to location of their poles on a circular curve of a unit radius, while use of blocks of numerical differentiation of current and voltage can result in running failure at alternate arcing ground. The application of the Goertzel algorithm for high-frequency components detection is proposed. It is implemented through an infinite impulse-response filter of the second order with two real coefficients in back coupling and one complex coefficient in circuit of direct relation. The results of simulation of the behavior of protection in the system of computer algebra Mathcad confirmed the reduction of calculation costs and stable work, regardless of the presence of aperiodic components at different initial phases of the voltage at the time of fault. As part of the protection, a trigger unit is provided that allows the operation if the voltage of the zero sequence exceeds the setpoint, which is 12‒15 % of the nominal value. In order to ensure reliable operation of the protection, permanent and arcing faults provide activationof protection impulses in the event of a fault. The positive results of protection algorithm were achieved on the mathematical model of the network as well as when testing a microprocessor prototype of a protective system in a laboratory environment.

Originality. For the first time for ground-fault protection in 6‒35 kV compensated networks, it is proposed to separate components of frequencies higher than fundamental frequency from the zero sequence voltage and currents using frequency filters created on the basis of the Goertzel algorithm are proposed; the algorithm is an improved modification of the Fourier transform; this increased the sensitivity, speed and stability of work protection.

Practical value.The mathematical model of the compensated electric network allows analyzing the behavior of protection at permanent and arcing ground faults. Selective protection from phase faults on the ground has been developed, which allows increasing the reliability of the power supply systems with a voltage of 6‒35 kV.

References.

1. Ghaderi, A., Ginn, H. L., & Mohammadpour, H. A. (2017). High Impedance Fault Detection: A Review. Electric Power Systems Research 143, 376-388. https://doi.org/10.1016/J.EPSR.2016.10.021.

2. Chen, K., Huang, C., & He, J. (2016). Fault Detection, Classification and Location for Transmission Lines and Distribution Systems: A Review on the Methods. High Voltage, 1(1), 25-33. https://doi.org/10.1049/hve.2016.0005.

3. Nikiforov, A. P. (2016). Optimization of control systems in a smart grid the power grid on the basis of generalization of information flows. Tekhnichna elektrodynamika, (5),64-66. https://doi.org/10.15407/techned2016.05.064.

4. Druml, G., Schegner, P., Fickert, L., & Schlommer, M. (2015). Advantages of the New Combination - Petersen-Coil and Faulty-Phase-Earthing. In 23rd International Conference on Electricity Distribution Lyon, 15–18 June 2015, (рр. 1-5). Retrieved from http://www.cired.at/pdf/CIRED2015_1450_final.pdf.

5. Ravlić, S., Marušić, A., & Havelka, J. (2017). An Improved Method for High Impedance Fault Detection in Medium Voltage Networks. Tehnicki Vjesnik – Technical Gazette, 24(2), 391-396. https://doi.org/10.17559/tv-20151012082303.

6. Wang, X., Song, G., Chang, Z., Luo, J., Gao, J., Wie, X., & Wie, Y. (2017). Faulty Feeder Detection Based on Mixed Atom Dictionary and Energy Spectrum Energy for Distribution Network. IET Generation, Transmission & Distribution, 12(3), 596-606. https://doi.org/10.1049/iet-gtd.2017.1250.

7. Altonen, J., Wahlroos, A., & Vähäkuopus, S. (2017). Application of Multi-Frequency Admittance-Based Fault Passage Indication in Practical Compensated Medium-Voltage Network. CIRED ‒ Open Access Proceedings Journal, (1), 947-951. https://doi.org/10.1049/oap-cired.2017.0967.

8. Venkataraman, K., Kirby, B., Hengxu, Ha., & Newman, P. (2014). Transient Earth Fault Detection on Compensated Earthed System. In 12 th IET International Conference on Developments in Power System Protection (DPSP 2014),31 March ‒ 3 April 2014. https://doi.org/10.1049/cp.2014.0034.

9. Pitot, F., & Vassilevsky, N. (2015). Wattmetric earth fault protection – innovation for compensated distribution networks. In 23 rd International Conference on Electricity Distribution Lyon, 15‒18 June 2015. Paper 0963. (pр. 1-5). Retrieved from http://cired.net/publications/cired2015/papers/CIRED2015_0963_final.pdf.

10. Syvokobylenko, V. F., & Lysenko, V. A. (2019). Microprocessor Selective Protection from the Phase to the Earth Fault in Electric Networks with Petersen Coil in Neutral. Tekhnichna elektrodynamika,(2), 54-62. https://doi.org/10.15407/techned2019.02.054.

11. Syvokobylenko, V. F., & Lysenko, V. A. (2018). Use of the Fourie transform algorithm for improving phase to the earth fault protection in distribution electric networks. Naukovi pratsi Donetskoho natsionalnoho tekhnichnoho universytetu. Seriia Elektrotekhnikai enerhetyka, 1(19) – 2(20).

12. Galanina, N. A., Dmitriev, D. D., & Akhmetzyanov, D. I. (2013). Goertzel algorithm for signals spectral analysis. Software systems and computational methods, 4, 376-383. https://doi.org/10.7256/2305-6061.2013.4.10543.

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ISSN (print) 2071-2227,
ISSN (online) 2223-2362.
Journal was registered by Ministry of Justice of Ukraine.
Registration number КВ No.17742-6592PR dated April 27, 2011.

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