Abstract： Multi-terminal HVDC transmission technology is one of the effective technical means to solve these problems. In order to meet the power distribution, voltage level and flexible scheduling requirements of different regions, establishing an interconnected power grid based on HVDC technology has become a popular trend. This paper first analyzes the operation control strategies of key equipment of the interconnected grid such as wind power, photovoltaic, DC/AC and DC/DC. Then, a multi-DC voltage level interconnected power grid with new energy is proposed, and its structural characteristics and operation principle are analysed. Besides, to isolate DC faults in different locations, a fault isolation strategy based on DCCBs is proposed. Finally, the simulation model is built under the PSCAD/EMTDC platform, and the simulation analysis of different working conditions is carried out to verify the effectiveness of the proposed operation control and DC fault isolation strategy.