The Reclose Scheme Matrix - A building block approach to more flexible reclose schemes

This tutorial based paper provides a unique perspective for adapting today´s distribution reclose schemes to modern IED (Intelligent Electronic Device) relays which continue to offer more innovative and flexible solutions. Due to the increased overhead of the IED´s configuration requirements that generally accompany these solutions, it is important to structure the settings and logic in such a way that custom solutions can easily be developed. The “Reclose Scheme Matrix” provides this structure. The matrix, a binary representation of the reclose system, is composed of building blocks that are used to design the reclose program. The rows of the matrix are defined by initiate and block signals, and the columns, by the shot pointer. By using building blocks, instead of fixed shots, a greater degree of flexibility can be achieved, allowing for multiple and adaptive sequences. For single pole reclosing, the initiate lines of the matrix can be represented on a per phase basis. The tutorial begins with a basic review of the fundamentals including why reclosing is needed, terms and definitions, and an example of how a typical fuse saving scheme is used to create the matrix. A discussion will then follow on specialized applications utilizing open interval time selectivity and drive to lockout features to fully demonstrate the flexibility and functionality of the reclose scheme matrix. The tutorial concludes with a section on testing and commissioning that emphasizes the benefits of an automatic reclose sequence visualization tool. The tool allows the user to view the settings from the reclose scheme matrix in table format and run test simulations by selecting various initiate input signals.