Facing the increasingly severe problems like short circuit current exceeding limit, serious AC-DC interaction and difficulty in setting up the third defensive line, system partition in multi-DC infeed receiving power grids like Guangdong power system is urgently required. In order to solve the contradiction between system partition and system stability and reliability, and support regional power consumption growth and large-scale clean energy access, an idea of building the outer ring of the Guangdong-Hong Kong-Macao Greater Bay Area is proposed. Key issues like coverage of the outer ring of the Bay, partition scheme of Guangdong power grid and capacity selection of the outer ring are specifically discussed. Then the flexible DC interconnection network scheme based on the outer ring of the Guangdong-Hong Kong-Macao Greater Bay Area is formed. Simulation analysis indicate that the scheme could meet the relevant safety standards, the capacity of Guangdong power grid could be increased to the expected level and problems such as short circuit current exceeding standards, serious AC-DC interaction and difficulty in setting up the third defensive line are effectively dealt with.