A Fast Protection Scheme Using Fault Current Characteristics in Multi-terminal Flexible DC Distribution Network

The fast and reliable detecting of DC faults and fault type identification is one of the key technologies for multi-terminal flexible DC distribution networks. In this paper, a DC reactor is used as the boundary component of the DC distribution network, based on the characteristics of fault current, a new protection scheme is proposed for multi-terminal flexible DC distribution network. This scheme uses the sudden change and the changing rate of fault current as the criterion to realize identification of the fault occurrence zone, and through the direction of the fault current to judge the fault type. The scheme can not only realize the rapid identification of DC line faults, but also can avoid the influence of line transition resistance and system operation mode Finally, a three-terminal flexible DC distribution network model is built in the PSCAD/EMTDC platform to verify the feasibility of the scheme under different DC faults.