The malfunction of DC arm overcurrent protection may lead to the failure of AC fault ride-through. And the action rejection or slow action of DC arm overcurrent protection may lead to overcurrent of switching device during a DC fault. For the above problems

this paper discusses the configuration of arm overcurrent protection function of the converter valve in the valve control device and the DC protection device and the coordination of arm overcurrent protection settings in flexible HVDC transmission system. According to the coordination diagram for AC protection settings

the optimized cooperation method of arm overcurrent protection function in the valve control device and the DC protection device is proposed. Finally

a simulation platform is built in PSCAD/EMTDC. The simulation result shows that the proposed coordination method can achieve AC fault ride-through. At the same time

the proposed coordination method and protection setting method can reliably block converter and trigger the bypass thyristor under severe faults like short circuit between DC poles

thereby reduce the risk of overcurrent of power electronic devices.