A novel current amplitude protection method for distributed generating system based on sufficient criterion theory

A novel protection and judgment strategy for distribution network with distributed generation (DG), which is known as the sufficient criterion protection, is proposed. It is hard for traditional protection methods to solve the problem of protecting the distribution network with grid-connected DG, so they have to be forced to decrease the efficiency of DG or increase the protection cost, however the proposed sufficient criterion protection aims at the extracted general fault feature and adopts simple and effective means to solve the problem. And because the proposed sufficient criterion protection is based on the fault feature, the judgment of the proposed protection is sufficient and reliable. For distribution network with grid-connected DG, the feature of the amplitude of the fault current is analyzed, and on this basis a current amplitude based sufficient criterion protection scheme is put forward and the detailed judgment method and its simulated validation are given.