Improved Ground differential relaying algorithm for the protection of a line-to-line fault of transformer

변압기의 선간 단락사고 보호를 위한 지락비율차동 계전 알고리즘의 성능향상 방법

Ground differential relay is used to provide fast, sensitive, and selective protection for the wye connected and grounded electrical power equipment such as generators, power transformers, and grounding transformers. The ground differential protection only protects the ground faults within the protection zone, so that it can't protect the line-to-line fault. This paper proposes the algorithm to provide the protection for the line-to-line fault through the ground differential protection. The proposed algorithm detects the line-to-line fault of transformer using the comparison between the positive and the negative current, when the ground differential relay dose not operate. The performance of the algorithm is verified using a PSCAD/EMTDC simulator under various case studies.