In conjunction with Xiamen flexible DC power transmission demonstration project

the scheme and engineering application of flexible DC control and protection system are researched

including the hierarchical structure of control and protection system

the basic control strategy of the pole control system

structure of control system

the interface features between the pole control system and the valve control system and the configuration of the DC protection system function. In order to verify the work correctness between the pole control system

the valve control system and the converter valves

and prevent large current appearing for the first time de-blocking from damaging the converter valves

this paper puts forward the passive inverter test scheme for the true bipolar topological structure system. Field test results have proved the validity of the triggering phase sequence by valve groups

fully compensating for the time delay of the control system. The results of reactive power and active power step test show that the control system meets the performance requirement on rapidity

reliability and flexibility. The results of DC protection trip test show that the logic function is correct

the converter valves are blocked correctly and the breaker trips correctly.