Detection failure elements in digital relay protection using the example of differential logic protection and the possibility of adaptive protection

Relevance. The efficiency and reliability of the relay protection system is influenced by many factors, such as: failure of the power switch, malfunction of the relay protection device components, errors in the operation of the current measurement, etc. These failures can lead to a complete failure of the protection system or incorrect protective action and, in the case of a short circuit, often result in damage to the protected object. Therefore, the development of more advanced methods for detecting failures in the protection system elements is crucial. THE

Purpose. The purpose of the article is to briefly analyze the problem of reliability in relay protection system in the event of a failure of protection elements, develop a new algorithm for the operation of longitudinal differential relay devices that detects current transformer failure (CT) on any side protected element, and recognizes network mode. The proposed algorithm allows relay protection devices to adapt when a CT failure is detected in each cycle, thus increasing the reliability of the protection system.

Methods. The algorithm is developed using mathematical logic methods. Protection devices utilize inter-station communication channels to exchange information with adjacent devices. Additionally , these devices automatically adapt their operating algorithm to the type failure that occurs, and reconfigure protection zones accordingly.

Results. The article examines the problem, and develops an algorithm for the automatic detection of failures in current transformer and relay protection circuits. This algorithm is based on Kirchhoff's first law and utilize an intersubstation information network. The proposed algorithm not only enables the unambiguous detection of such failures, but also allows for the instant adaption of differential relay protection zones when necessary, ensuring the speed relay protection is maintained . The algorithm has been validated through testing in the PSCAD/EMTDC program using a case study of busbar differential protection.

Conclusion. As a result of the research, significant findings have been obtaine that can be enhance the reliability of the digital relay protection system in the event of failures in protection elements.

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