Study on the evaluation index for the strength of different structural forms of AC/DC system

With the continuous promotion of the global energy Internet, the power grid interconnection across regions and countries needs long distance and large capacity power transmission. UHVAC or UHVDC is the main transmission technology. Reference to China's domestic operation experience, with the rapid development of electric power system, large capacity UHVDC construction faster and faster, if the construction of AC system is relatively lagging behind, there will be a “strong DC with weak AC” problem. Through the study, we view from the grid planning point, optimize the power grid structure to solve the problem. In this paper, based on the analysis of the interaction mechanism of AC and DC in different structural forms and the classification of safety and stability of power grid, puts forward three types of indicators for power grid strength evaluation. And through the actual grid example, the correctness of the proposed evaluation index system is verified, which provides a strong guarantee for the planning and development of power grid.