1. NARI Group Corporation(State Grid Electric Power Research Institute), Nanjing 211106, China; 2. State Key Laboratory of Smart Grid Protection and Control, Nanjing 211106, China;3. College of Energy and Electrical Engineering, Hohai University, Nanjing 210098, China; 4. State Grid Jiangsu Electric Power Co., Ltd., Nanjing 210000, China

The protection partition and protection configuration are studied based on the typical flexible DC distribution network. According to the fault characteristics of DC lines, the protection scheme of DC pole-to-pole short-circuit fault, single-pole grounding fault and broken line fault are analyzed, and a comprehensive fault location method based on differential protection and multi-point direction information is proposed. Based on the proposed protection and fault location scheme, the protection device of DC distribution network which has high sample rate and multiple kinds of analog input interfaces is developed. The test and dynamic simulation on real-time digital simulation(RTDS)system prove the feasibility of the protection scheme and correctness of the fault location method, and the action behavior and performance index of the developed protection device meet all the safety operation requirements of DC distribution network.