Analysis and Calculation of Ac Fault Characteristics of New Energy Transmission System Through Dc

The control characteristic of the flexible DC converter station and the wind turbine grid side converter is very different from the traditional AC transmission after the AC fault occurs in the flexible DC transmission system of offshore wind power. Therefore, it is necessary to have a fault calculation. In order to solve this problem, the fault equivalent model of the whole AC system is established based on the low voltage ride through strategy and the corresponding fault calculation method is derived. Firstly, the AC fault characteristics of offshore wind power system via flexible DC are qualitatively analyzed. Then, based on the control characteristics of the system during the fault period, the fault equivalent model of the entire AC system is established, and the corresponding fault calculation formula is derived based on the fault equivalent model. Finally, the effectiveness of the proposed method is verified by PSCAD/EMTDC simulation based on the fault degree and fault location.