Study of the short circuit current contributed by a DC system with a three-phase fault on the AC side of an inverter

Currently, the standards used to calculate the short circuit (SC) current ignore the contribution of DC systems to the SC current when short-circuit faults occur in an AC systems. With the rapid development of High Voltage Direct Current systems (HVDC), it has become important to determine whether the contribution of the HVDC system can be ignored when calculating the SC current. This study investigates the transient processes of a line-commutated converter HVDC (LCC-HVDC) system with a three-phase fault on the AC side of an inverter. The mechanism of the SC current contributed by LCC-HVDC is analyzed, and a practical method for calculating the SC current is proposed. Simulation results verify the proposed mechanism and the accuracy of the method.