Research On Robustness Analysis And Defense Strategy Of Power System

With the rapid development of smart grid,while bringing great convenience to human society,its potential dangers are also increasing.In recent years,the occurrence of blackouts has brought serious damage to human society,which makes more and more scholars begin to pay attention to the problem of cascading faults in the power system.It is of great significance for the construction of a robust smart grid to pay attention to the cascading faults in power systems,suppress the transmission of cascading faults,find vulnerable parts in the power grid system and propose targeted prevention and control strategies.Based on the theoretical system of complex networks,this paper conducts experimental modeling and analysis on the cascading faults in the power grid.Analyzes the changes of the specific robustness of the power grid system after being attacked,and proposes Specific defense strategies to reduce the propagation of cascading faults,so as to build a robust power grid system.The specific summary of this paper is as follows:(1)Aiming at the fault problem caused by the cascade propagation of the power grid system,a grid cascade failure model with active defense strategy is proposed based on the existing electrical dielectric model,and its robustness is analyzed experimentally.The model adopts the distribution principle of "the most capable people do more work",and is closer to the actual physical and electrical characteristics of the power grid by adjusting the distribution method of the load propagation of the failed nodes.The active defense strategy proposed in this paper can reduce the electrical dielectric of most nodes in the overall power grid when a fault occurs by removing a small number of nodes with large “removal weights”,and achieve the effect of restraining the further spread of grid cascading faults,so as to improve the network robustness and build a robust smart grid.(2)Firstly,the impacts of attack modes,different allocation parameters and tolerance parameters on the system robustness are studied by using IEEE118 and IEEE300 power system simulation.Then,through the introduction of active defense strategies,improve the robustness of power grid system and reduce the occurrence of cascading faults.In this paper,two evaluation criteria are used to evaluate the robustness of power grid system from two aspects: connectivity and charge loss ratio.Experiments show that when the tolerance parameters are fixed,the optimal allocation parameters can be found by adjusting the allocation parameters of the faulty nodes,and the propagation of the fault in the network can be reduced.It is found that there is a threshold value of for different allocation parameters .Under this threshold,the network has little change in the degree of external interference,and always has strong robustness.Therefore,by adjusting the tolerance parameters and load distribution strategy,the network can always have strong robustness,and at the same time,the cost of grid construction can be reduced.Finally,by introducing an active defense strategy to actively remove a small number of nodes with large "removal weights",the spread of grid cascading faults can be better suppressed,which shows that the active defense strategy is a more economical and effective prevention method to prevent the grid system from being attacked than the existing methods.It is worthy of further research and application.At the same time,it indicates that the cascading failure can be better prevented by starting from the improvement of the network structure itself.(3)Based on the analysis of the single-layer power grid system,the cascade failure model of the double-layer grid and information network is established.The IEE118-BA118 and IEEE300-BA300double-layer network systems are selected for experimental simulation,studying different types of node connections in the double-layer network and the influence of different inter-layer connections on the system robustness.Through experimental simulation,grid node failure and the influences of information network node failure on the inter-layer network and intralayer network are analyzed,which is closer to the real cascade fault propagation of smart grid.Then,adopt the different evaluation criteria from the single-layer grid to evaluate the robustness of the double-layer network.Studies shows that it is an effective means to enhance the robustness of the double-layer network in grid-information network by appropriately increasing the inter-layer connections of the double-layer network.