A Digital Protection Procedure for Smart Grid Reconfiguration after Faults

Smart grids can be considered as active, meshed networks. In order to increase the continuity level of power supply in these systems, it is of fundamental importance to quickly detect the presence and location of a fault and afterwards to reconfigure the network automatically, eliminating the faulted line-segment as fast as possible. Therefore, it is particularly important to draw up a selectivity plan which could prove accurate and valid for most possible faults. From this point of view indeed, the use of a proper selectivity coordination and the adoption of new-generation digital relays may substantially increase the supply continuity level of smart grids, which are being more and more widely implemented. The paper presents a fast, robust method based on a particular logic selectivity procedure that can be advantageously used also in the presence of Distributed Generation (DG). Moreover, the operation zones and setting of the proposed digital protection system are presented and explained. Finally, some problems of protection systems in the presence of DG are also discussed and commented.