With the rapid development of power grid construction, the impact of power grid accidents is also gradually increasing. Power grid security has attracted increasing attention. Multiple weakening of the grid structure is one of the high-risk scenarios, and one which is likely to cause large-scale power outages. The closed-loop management and control system of power grid security risks is essential for the stable operation of the power grid. Taking 7 major and relatively large power grid security risks of the Enshi Power Grid as an example, this paper analyzes the causes and prevention methods of each power grid security risk. An overall deduction is made based on a summary of the characteristics and implementation effects of various risk prevention measures. What is needed is a multi-closed-loop management and control system for grid security risks that responds to high-risk scenarios. Through the implementation of multiple closed-loop feedback and optimization of risk assessment and coordinated prevention and control links, the goal of avoiding and reducing the risk of grid accidents is achieved. Finally, an example of the Huanggang Central and Southern Power Grid is given to verify the effectiveness of the proposed closed-loop management and control system for power grid security risks. This work is supported by the National Natural Science Foundation of China (No. 52022035) and the Science and Technology Project of State Grid Hubei Electric Power Co., Ltd. (No. 521505190001).