Pole-to-ground Fault Analysis for the DC Distribution System Considering the VSC Control Modes

In DC distribution system, the unblocked converters after line faults can improve the reliability of DC power supply. The fault mechanism considering unblocked converters is affected by the control modes of converters. In this paper, with the promise that the converters will not be locked after fault, the fault mechanism and characteristics of pole-to-ground fault under the constant DC voltage control, constant AC active power control and droop control are analyzed. The conduction process of diodes and IGBTs with unblocked VSCs are analyzed. The simulation analysis is carried out on the PSCAD/EMTDC platform. The study of the fault mechanism can provide a theoretical basis for the protection of the DC distribution system.