Faulted Feeder Selection Based on Active Harmonic Injection of CIDGs for Small Current Grounding System

When a single-line grounding (SLG) fault occurs in a small current grounding system (SCGS), the weak fault characteristics pose a challenge to the fault line selection (FFS). To improve the reliability of FFS, a new FFS method based on harmonic active injection of converter interfaced distributed generator (CIDG) is proposed in the paper. First, by analyzing the distribution law and attenuation characteristics of the harmonic current actively injected by CIDG in the system, the active injection characteristic harmonic current signal that can meet the needs of FFS is selected, and then, a characteristic harmonic current signal injection method based on CIDG active control is designed. On this basis, an FFS method based on the amplitude-phase relationship of harmonic current is proposed, enabling the method to simultaneously meet the requirements of fault line selection and phase selection requirements. PSCAD/EMTDC simulation analysis verifies the effectiveness and superiority of the proposed method compared to existing methods.