H. Shateri, S. Jamali,
Volume 2, Issue 3 (7-2006)
Abstract
This paper presents the effects of instrument transformers connection points on
the measured impedance by distance relays in the presence of Flexible Alternating Current
Transmission System (FACTS) devices with series connected branch. Distance relay
tripping characteristic itself depends on the power system structural conditions, pre-fault
operational conditions, and especially the ground fault resistance. The structural and
controlling parameters of FACTS devices as well as the connection points of instrument
transformers affect the ideal tripping characteristic of distance relay. This paper presents a
general set of equations to evaluate the measured impedance at the relaying point for a
general model of FACTS devices to consider different affecting parameters.
M. Mollanezhad Heydar-Abadi , A. Akbari Foroud,
Volume 9, Issue 3 (9-2013)
Abstract
Fault classification in distance protection of transmission lines, with considering the wide variation in the fault operating conditions, has been very challenging task. This paper presents a probabilistic neural network (PNN) and new feature selection technique for fault classification in transmission lines. Initially, wavelet transform is used for feature extraction from half cycle of post-fault three phase currents at one end of line. In the proposed method three classifiers corresponding with three phases are used which fed by normalized particular features as wavelet energy ratio (WER) and ground index (GI). The PNNs are trained to provide faulted phase selection in different ten fault types. Finally, logic outputs of classifiers and GI identify the fault type. The feasibility of the proposed algorithm is tested on transmission line using PSCAD/EMTDC software. Variation of operating conditions in train cases is limited, but it is wide for test cases. Also, quantity of the test data sets is larger than the train data sets. The results indicate that the proposed technique is high speed, accurate and robust for a wide variation in operating conditions and noisy environments.
