Abstract: On August 15, 2023, a large area of power outage occurred in Brazil, which seriously affected the normal operation of the economy and society. The accident exposed the weak structure of Brazil's power grid, insufficient power support, imperfect technical defense line, safety control and other problems, and brought many revelations for China's power grid safety and construction of new power systems.To simulate the entire process of power outage development in Brazil,based on the large power grid online security analysis and application platform, this paper adjusts the operation mode of Shanxi power grid, weakens the grid structure, increases the output of new energy in the north and sets complex chain faults including DC lock-out in the northern part of the new energy, so that the power grid is divided into two areas in the north and south, and adopts security control measures such as low-frequency load shedding, out-of-step splitting, and high-frequency generator cutting to restore the safe and stable operation of the power grid which has certain guiding significance for daily control and operation work.