Aiming at the voltage source converter based high voltage direct current (VSC-HVDC) transmission project with bipole configuration using full-bridge submodule (FBSM) and half-bridge submodule (HBSM) hybrid converter valve

firstly

the impact of converter valve and charging resistor on the fault characteristics and protection of VSC-HVDC during start-up is analyzed. And then

the fault circuits at different stages and positions of AC charging process are analyzed. Taking the typical parameters of a VSC-UHVDC project for example

the electromagnetic transient simulations are carried out. Combined with the obtained fault current from simulation

the DC protection scheme is proposed. Finally

the suggestions for DC protection configuration and converter station wiring in VSC-UHVDC transmission project are given. The researches show that the fault current limited by the charging resistor affects the charging protection

and the fault characteristics of FBSM and HBSM hybrid converter valve are different at different stages

but these fault could be reliably detected by DC protection including the charging resistor overcurrent protection

and there is no need to set isolation switches between the converter transformer and the converter valve for the first live test of converter transformer.