Fault identification scheme for hybrid multi-terminal HVDC system based on control and protection coordination strategy

To further improve the capability of fault identification for protection and adaptive reclosing, a fault identification scheme based on a control and protection coordination strategy for a hybrid multi-terminal HVDC system is proposed. The protection principle for fault isolation is constructed based on the difference of the polarity characteristic of fault current between the fault line and non-fault line in the uncontrolled fault stage and fault current limiting stage. In the adaptive reclosing stage, an active fault identification scheme based on the amplitude distribution law of the injection signal along the line is proposed. Intensive simulation studies prove the fault identification scheme can identify the fault area in various fault scenarios and identify permanent faults to carry out adaptive reclosing.