Fault Location Estimation in Voltage-Source-Converter-Based DC System: The L Location

This article presents a new method for estimating the fault location in a voltage-source-converter-interfaced dc system. The proposed dc fault location estimation method evaluates the distance from the fault point to the dc line terminal by estimating the line inductance; hence, it is designated as L location. Since the fault impedance usually only includes resistance, the proposed L location is less affected by the variation of fault resistance. In addition, the ripple caused by the distributed capacitive discharge is excluded from the dc line current when the proposed L location is applied in the dc system with the distributed-parameter transmission line. The cubic curve-fitting method is used to reconstruct the current signal based on the least squares method. The effectiveness of the proposed L location is verified with an OPAL-RT-based multiterminal dc (MTDC) system and experimental point-to-point and MTDC systems. The comparison with the impedance estimation, the voltage-traveling-wave-based location, and the differential and directional protection substantiates the integral performance of the proposed method