A NEW METHOD TO ENHANCE THE DIFFERENTIAL PROTECTION OF THE MICROGRID BY SELF-BACKUP PROTECTION

Abstract

Although the differential protection schemes consider as one of the effective types to protect the microgrid, this method may result in inaccurate performance because of the loss of communication link connecting the two ends of the line or other reasons. Therefore, the use of backup protection can lead to more accurate results. In this paper, self-backup protection is presented to cover the mal-operation of main protection. In this scheme, a new R-ratio method is defined based on the summation of the three-phase currents and the minimum of the three-phase voltages to overcome the low fault current during the islanded microgrid. The proposed scheme can detect all fault types during both operation modes of microgrid, grid-connected and islanded for radial and loop configuration. The validation of the proposed scheme is performed using PSCAD/EMTDC software. The simulation results proved that the proposed scheme could provide adequate protection against various fault types in grid-connected and islanded operation modes for a radial and loop configuration.