Algoritmos de proteção de distância para linhas de transmissão longas paralelas equilibradas

Abstract

This doctoral dissertation proposes novel first-zone distance protection algorithms adequate for balanced long parallel transmission lines connected to either common or independent buses at both ends. The proposed algorithms are based on distributed parameter line models, in which the capacitive, propagation, and zero-sequence mutual coupling effects are fully considered. The exactness of the obtained formulations has been proved using symmetrical components and graph theory, being the test systems modeled exactly like they were considered for the derivation of such algorithms. The applicability of the constant zero-sequence compensation parameters approach has also been attested, demonstrating that the proposed algorithms can satisfactorily use analytical expressions, avoiding the need of iterative methods. In addition, extensive tests were performed, including performance comparisons between the proposed and conventional algorithms. The fault resistance impact for different terminal systems and pre-fault load levels, the overreach for external faults, the sensitivity to errors in zero-sequence parameters, the appropriateness of an approach to avoid false operations, and the influence of zero-sequence mutual coupling modeling were verified. In view of the results obtained, it is suggested the implementation of the proposed algorithms in commercial numerical relays, instead of the conventional algorithm, functioning in an adaptive scheme in conjunction with auxiliary modules existing in literature for high fault resistance detection.