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Mitigation of Current Transformer Residual Flux to Optimize the Current Transformer Core Dimension (in Auto-Reclose Scheme)
, M.Sc. Thesis Sharif University of Technology ; Vakilian, Mehdi (Supervisor)
Abstract
Residual flux in a current transformer (CT) could result in CT saturation while short-circuit faults occur. This phenomenon causes unreliable operation of protective relays. This problem gets worse especially when autoreclosure scheme is used. In this research, a novel method is proposed for the mitigation of CT residual flux in duration of reclosing dead time. This method is implemented by a low-voltage dc source, a suitable power-electronic switching unit (inverter), and a simple and efficient controller. In the proposed method, the dead time of reclosing is detected based on a least error squarer (LES) filter. Then switching controller leads the CT to both opposite saturation regions and...
Impacts of loop restoration strategy on distribution system reliability
, Article 2009 IEEE Bucharest PowerTech: Innovative Ideas Toward the Electrical Grid of the Future, 28 June 2009 through 2 July 2009 ; 2009 ; 9781424422357 (ISBN) ; Fotuhi Firuzabad, M ; Sanaye Pasand, M ; Lehtonen, M ; Sharif University of Technology
Abstract
Implementation of Distribution Automation (DA) in electric power distribution systems can result in customer satisfaction with improved reliability, consistent quality and high-tech services. Loop Restoration Strategy (LRS) is a special DA method in the feeder level which is used by electric utilities to improve distribution system reliability. The effects of the implemented LRS on the reliability indices of a given distribution system mainly depend on its Automatic Control System (ACS). Selecting the type of ACS of LRS by electric utilities relies on the level of improvement required at load points and system oriented reliability indices. A step by step evaluation procedure is proposed in...