Análisis de comportamiento del RELÉ SEL-421 en un sistema de transmisión en paralelo de 500KV con acoplamiento mutuo

Abstract

This document addresses the analysis of the behavior of the SEL-421 relay in a 500 kV parallel transmission system with mutual coupling—an essential aspect in electrical engineering for the protection of transmission lines. The analysis focuses on how mutual coupling induces an electromagnetic phenomenon in parallel lines, where one line can induce voltages and currents in another, affecting the relay’s measurements during operation under various network faults. The study aims to evaluate the influence of this phenomenon on the protection provided by the SEL-421 relay and propose adjustments to optimize its performance. The proposed methodology involves detailed simulations in Digsilent to model the relay’s behavior under different fault scenarios. These simulations are followed by physical laboratory tests to validate the accuracy of the relay’s response, using the OMICRON CMC356 equipment. The analysis of the obtained results is thoroughly documented, allowing for a direct comparison between simulated values and those obtained in real-world tests. The study results indicate that the SEL-421 relay offers efficient protection for most faults, provided that prior analysis is conducted regarding the effects of mutual coupling in parallel lines. These effects can directly impact measurements, causing the relay to operate incorrectly. In conclusion, the SEL-421 relay is an effective equipment for transmission line protection. However, its optimal performance depends significantly on careful configuration that considers the various effects that may arise in the network. Periodic adjustments to relay parameters and complementing simulations with practical tests are recommended to ensure reliability under all operating conditions.