A Superimposed Current Based Unit Protection Scheme for DC Microgrid

With enhanced processing capacity and communication infrastructure available in smart grid platform, unit protection scheme is a promising technique. High resistance fault is a problem with current differential and current direction based unit protection solutions. In this letter, a protection scheme capable of fast fault detection and reliable selectivity for DC microgrid is proposed. The method uses superimposed currents of both ends of a line segment presented on \Delta i -plane during fault to derive protection decision. Using PSCAD/EMTDC simulations, performance of the proposed method is evaluated, compared and found to be accurate.