Fault current limitation problem has become one of the major effects which constrain the development of DC transmission network. As the voltage level increase, increasing rate of fault current is becoming higher, adding to the topology of DC transmission network is getting complex, a network contains different voltage level transmission lines/cables is the inevitable result of the development trends. Under this condition, DC/DC transformer which acts as the link between two voltage levels will plays an important role in not only the power flow control but also fault current limitation and protection. This paper provides a novel topology and control method based on dual active bridge (DAB) DC/DC transformer which has function of fault current limitation in order to insulate the fault condition from one side of the transformer to another.