A New Protection Scheme for DC Substation System Based on Single-ended Measurement

In order to meet the selectivity and the speed requirement of DC protections, this paper proposes a new DC protection scheme for DC substation systems. This scheme is developed based on the single-ended natural variation characteristics of DC current and its first and second derivatives under fault transients. It extracts the transient characteristic difference between the internal fault and external fault to realize the fault identification. The proposed scheme can identify internal fault or external fault quickly without communication, which satisfies the speed, reliability and selectivity requirements of the protection. Tests on PSCAD/EMTDC was carried out to verify the feasibility and superiority of the proposed scheme.