Wavefront-based protection for active distribution grids

Installation of distributed generation in distribution grids may cause malfunctioning of conventional protection systems due to bidirectional flows and increased range of short-circuit current levels. Despite considerable efforts to address these challenges, development of low-cost, high-speed and reliable protection systems for active grids remains an open research question. This paper presents a new wavefront-based protection system for medium voltage lines of a substation in an active grid. The protection does not require voltage measurements and relies only on local current measurements and binary signals received from neighboring protection terminals. The fault occurrence is detected by capturing fault-generated current waves using Wavelet Transform. A faulted line in the protection zone is identified through comparative analysis of slopes' signs of current wavefronts obtained locally and from neighboring terminals. The proposed algorithm potentially offers high-speed and reliable protection of any number of interconnected lines, which is demonstrated on the IEEE 34-bus distribution system.