Robustness Analysis And Optimization Method Of Power Grid Considering Cascading Faults

With the growing demand for electricity and the continuous expansion of the grid scale,ensuring the security of the power grid has become a vital issue.In recent years,cascading failures in the power grid have occurred from time to time,which have seriously affect people's life.In order to ensure the safety and reliability of the power grid,the analysis and optimization of the robustness of power grid during cascading failures is of great significance.Based on the theory of network science and evolutionary computation,we conduct specific researches from the perspective of vulnerability assessment,topology optimization and resource allocation,respectively.Our main contributions are as follows.(1)We assessed the vulnerability of the power grid against cost-constrained hybrid attacks.We formulate a cost-constrained hybrid attack in power grids,where both nodes and links are targeted with a limited total attack cost.Based on the consequence and cost of removing a component(node or link),we propose an attack centrality metric for components.We formulate a cost-constrained hybrid attack optimization problem and prove that this optimization problem is NP-hard.We further propose a greedy hybrid attack and another optimal hybrid attack by applying the attack centrality.Simulation results on IEEE bus test data demonstrate that the optimal attack based on the local attack centrality has the best performance.(2)We studied the impact of the link connection and the allocation of loads on the cascading failures of the cyber physical power system.We considered a framework which consists of two networks that have inherently different characteristics governing their interdependence and assessed the robustness of the system against random attacks.The simulation results show that the cyber physical power system with a larger number of links between the two networks achieves lower robustness on the whole.The system with equal redundant space allocation is more robust than one where redundant space is proportional to load whether the links between two networks are partial or one to one correspondence.(3)We studied the effect of resource allocation to the recovery of power grids during cascading failures.We proposed a load-based resource allocation scheme for power grids and studied the impact of the scheme on the recovery process under the constraint of a fixed amount of total resources.Simulation results show that excessive allocation of recovery resources to high-load or low-load nodes cannot improve the system's recovery performance.Furthermore,we provided an optimal resource allocation scheme using particle swarm optimization algorithm.The simulation results demonstrate that the optimal scheme is more efficient.