Prevention of Maloperation of the REF Relays Using Artificial Intelligence and Wavelet Transform

Document Type : Research Paper

Authors

1 Faculty of Electrical and Computer Engineering (ECE), Semnan University, Semnan, Iran.

2 Faculty Electrical and Computer Engineering, Babol noshiravani University of Technology, Babol, Iran.

10.22075/mseee.2024.33363.1148

Abstract

Restricted Earth Fault (REF) Relay, a type of differential protection, is responsible for detecting single-phase-to-ground faults at the terminal of a transformer or faults in the winding to the core. This protection scheme is inherently sensitive and rapid; however, due to current transformer saturation during external fault conditions with high currents and the transient magnetizing current flowing through the transformer core, it may be susceptible to false operation. In this paper, an intelligent restricted ground fault protection scheme based on wavelet transform (WT) is presented. In the initial step, the differential current resulting from simulation is analyzed using WT, and various features of decomposed signals are extracted as sample patterns for training intelligent classifiers. The performance of the proposed method is evaluated using data obtained from the simulation of a 230/63.5 kV power transformer in the PSCAD/EMTDC software environment. Additionally, to accurately simulate the transformer current during saturation, the valid Gill's model is employed. The results of implementing this intelligent protection scheme confirm its high reliability against false operation.

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Articles in Press, Accepted Manuscript
Available Online from 01 July 2024
  • Receive Date: 23 February 2024
  • Revise Date: 17 March 2024
  • Accept Date: 01 July 2024