Cable fault characterization in VSC DC systems

Voltage source converter (VSC) DC systems are a new and emerging technology. They offer advantages over AC systems but also pose concerns, such as transient fault currents. VSCs are not protected against very fast-transient overcurrent caused by DC cable faults. In order to design protection systems for prompt interruption and isolation of these faults, DC system behavior under fault conditions must be studied. This paper investigates two-level VSC DC system response to DC cable faults and provides analytical expressions for characterizing DC fault overcurrent and voltages and identifying main DC fault characteristics (i.e., type, distance and resistance). This study is a useful tool for further DC system protection design.