Adequacy and safety comprehensive evaluation for ultra-high voltage AC/DC mixed power grid

Combining actual demands for ultra-high voltage (UHV) power grid of our country electricity production, power collection, electricity transmission and distribution, functions, adequacy and reliability of different UHV power grid projection are discussed in this paper. They were discussed that differences in function and reliability of different UHV power grid structure, and the development necessity, feasibility and rationality of UHV AC/DC power grid in China. Power supply capacity adequacy and security of different power grid were discussed complementally in the aspect of system reliability. It is shown that the UHV AC/DC transmission grid with strong frame is superior relatively to meet the performance of transmission demand in China. In terms of system security complexity, cascading failure conditions and the complexity of power system blackouts were expounded. It is pointed out that the defect of power system security defense system is an important reason leading to large scale power system blackout. While constructing the UHV AC/DC power grid, it is necessary to establish a new generation of power system security monitoring system to improve the security and defense system of large-scale power grid.