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A Study on SCOTT Transformer Protection Relay Malfunction Case and Improvement Methodology

스코트 변압기 보호계전기 오동작 사례분석 및 개선방안 고찰

  • Lee, Jong-Hwa (Department of Railroad Electrical System Engineering, Woosong University) ;
  • Lho, Young-Hwan (Department of Railroad Electrical System Engineering, Woosong University)
  • 이종화 (우송대학교 철도전기시스템학과) ;
  • 노영환 (우송대학교 철도전기시스템학과)
  • Received : 2017.06.20
  • Accepted : 2017.07.07
  • Published : 2017.07.31

Abstract

In Korean AC power railway substations, SCOTT winding transformers are under operation to have a single phase power supply together with a phase angle of $90^{\circ}$ on the secondary side of the main transformer. In the case of an internal fault of the transformer, the transformer protection relay should be cut off on the primary side, the transformer should be inoperative to the external fault of the transformer or to the normal train operation. Reducing the malfunction of the relay through an exact fault determination is very important for securing a stable power system and improving its reliability. The main transformers are protected using Buchholtz's relay and a differential relay as the internal fault detection devices, but there are some cases of the main transformer operation under the deactivation of this protection function due to a malfunction of the differential relay. In this paper, the characteristics of the SCOTT transformer and differential relay as well as the malfunctioning of the protection relays are presented. The modeling of the SCOTT transformer protection relay was accomplished by the power system analysis program and the Comtrade file from 'A substation', which was used as the input data for the fault wave, and the harmonics were analyzed to determine if the relay operates or not. In addition, an improvement plan for malfunctioning cases through wave form analysis is suggested.

Keywords

Buchholtz's relay;differential relay;malfunctioning;protection relay;railway substations;SCOTT

Acknowledgement

Supported by : 국토교통부

References

  1. Jung Chul Kim, "Analysis on feeding system and Understanding on the electrical characteristics of the korean railway", Gidari, pp. 18, 2008.
  2. IEEE Std C37.91, 'IEEE Guide for Protecting Power Transformer', pp. 19, 2008.
  3. ICE, "DIGITAL MULTI-FUNCTION RELAY DIFFERENTIAL PROTECTION FOR TRANSFORMERS NPDT USER'S GUIDE", pp. 11, 2009.
  4. CIGRE Working Group C4.307, "Tranformer Energization in Power System : A Study Guide", 2014.
  5. Steven Hodder, Bogdan Kasztenny, Normann Fischer, and Yu Xia, "Low Second-Harmonic Content in Transformer Inrush Currents - Analysis and Practical Solutions for Protection Security", 67th Annual Conference for Protective Relay Engineer, 2014. DOI: https://doi.org/10.1109/CPRE.2014.6799037
  6. Kyoung-Ho Kim, Jong-Hweon Lee, Kyeong-Yeol Kim, "The method of the regenerating COMTRADE data using PSCAD", Conference for The Korean Institute of Electrical Engineers, pp. 584-585, 2014.
  7. Chul-Won Park, "Power Transformer Modeling and Transient Analysis using PSCAD", The Transactions of the Korean Institute of Electrical Engineers vol. 65P, no. 2, pp. 122-129, 2016. DOI: https://doi.org/10.5370/KIEEP.2016.65.2.122 https://doi.org/10.5370/KIEEP.2016.65.2.122