Cascading fault prevention and control strategy based on economic dispatch of AC/DC systems

To effectively prevent cascading failures during the economic dispatch of AC/DC systems, this paper proposes a preventive control strategy that considers both safety and economic factors and establishes a nonlinear bilayer optimization model. First, based on the action characteristics of relay protection, a mathematical method for determining cascading trips is presented. Second, using the active power output of units as a control variable, a static security margin index that measures the safety level of AC/DC systems is established. An economic indicator is then given by comprehensively considering network loss, unit power supply cost, and environmental governance cost. To address the issues of the sparrow search algorithm falling into local optima and insufficient convergence accuracy, an improved sparrow search algorithm is proposed by integrating improved Circle chaos, spiral search, the Levy flight strategy, and mutation perturbation. Standard test functions are used for comparative analysis with other algorithms to demonstrate the effectiveness of the proposed algorithm. Next, this paper employs this algorithm to solve the aforementioned bilayer preventive control model using a Jacobian matrix preconditioning method combined with sparse storage technology in power flow calculations to improve computational efficiency. Finally, the improved IEEE 39-bus system is used for simulation analysis of the proposed algorithm and model, verifying the feasibility of the proposed strategy.