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

This paper presents a new method for estimating the fault location in 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 square method. The effectiveness of the proposed L location is verified with an OPAL-RT based multi-terminal dc system and experimental point-to-point and MTDC systems. The comparison with other methods, including the impedance estimation and the voltage travelling wave based location substantiates the comprehensive performance of the proposed method.