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Estimation of travelling wave arrival time in longitudinal differential protections for multi‐terminal HVDC systems
Author(s) -
Johannesson Niclas,
Norrga Staffan
Publication year - 2018
Publication title -
the journal of engineering
Language(s) - English
Resource type - Journals
ISSN - 2051-3305
DOI - 10.1049/joe.2018.0225
Subject(s) - computer science , compensation (psychology) , reliability (semiconductor) , terminal (telecommunication) , fault (geology) , traveling wave , signal (programming language) , differential (mechanical device) , real time computing , time of arrival , control theory (sociology) , electronic engineering , telecommunications , engineering , power (physics) , channel (broadcasting) , artificial intelligence , mathematics , control (management) , psychology , mathematical analysis , physics , quantum mechanics , aerospace engineering , seismology , psychoanalysis , programming language , geology
Multi‐terminal high‐voltage DC (HVDC) systems equipped with HVDC breakers require that detection and clearing of faults occur within a few milliseconds. Although detection without communication is generally preferred with regard to detection delay and simplicity, detection schemes relying on communication can enhance the overall performance due to their reliability. One such principle is the travelling wave differential protection that is based on the comparison of waves at both ends rather than solely on current. However, as with conventional differential protections, some kind of synchronisation must be applied to properly compensate for the time difference between samples obtained at different geographical locations. In this study, a synchronisation algorithm is presented that applies real‐time signal processing to automatically obtain a proper compensation between the signals from both ends. The algorithm is examined by injection of data samples, generated from the simulation of an external fault in a PSCAD/EMTDC model. Additionally, the suitability for a real‐time implementation is evaluated by execution time estimation using a simulated DSP. The algorithm is found to perform well, not only in identifying the compensation delay but also in terms of computational efficiency, thus allowing for real‐time application.