Current index based protection technique for low voltage DC microgrid

•This method is fast and requires only current samples to find the current index (CI).•The coefficient of CI is employed to classify the fault as an internal or external.•It is adopted a dedicated communication protocol to enrich the security and reliability.•The proposed protection algorithm works effectively even during high resistance fault.•Comparative study of proposed method with the methods in literature has been done. In recent days, the penetration of power electronic converters in microgrid is expecting fast operation of the protection schemes for healthy operation of the power electronic devices. The threshold selection based protection methods are system dependent which may not be reliable. In addition, protection methods based on the principle of overcurrent and reversal of current direction are not preferable for DC microgrid protection. Moreover, protection coordination is one of the challenge in case of failure communication. This article proposes a simple algorithm that utilizes only local current samples to achieve above mentioned challenges. The central controller enhances the reliability of protection system by providing backup operation in case of communication failure. This method adopts polarity of the current index obtained at each end of the line segment in the DC microgrid to recognize and isolates the faulted line promptly. The dissimilar abnormal cases like different operating modes, load changes, faults at different line locations with various system configurations and different fault resistances have been simulated in the MATLAB/Simulink tool to test efficiency of the proposed method. A comparison of the proposed method with existing methods has been made to examine the accuracy in dependability and reliability.