DC Line And Converter Attacking Considered Resilience Analysis Of AC/DC Hybrid Distribution Network

In recent years,extreme events such as natural disasters and man-made malicious damage occur frequently,resulting in large-scale power system failure.It has become the consensus of all countries to build a resilient power grid with good ability of preparation,absorption and adaptation.At the same time,based on the traditional AC distribution network,AC/DC distribution method has gradually become a popular direction of future distribution network development.The concept of power resilience is employed to study its capability to reduce fault loss and restore power supply in face of extreme events disturbance,which is of great significance to adapt to the trend of power grid development and protect the production and livelihood of people.Firstly,the analysis methods of distribution network resilience are presented.The research category of AC/DC resilience is defined,and the resilience index considering robustness and rapidity is described based on the resilience evaluation matrix.Besides,from the aspects of fault components,power flow calculation and fault mechanism,the differences between AC/DC distribution network and traditional AC distribution network are researched.Also,the corresponding new strategies suitable for AC/DC scenarios are derived.Secondly,on the foundation of traditional attack-defense(AD)model,a defense-attack-defense(DAD)tri-level resilience promotion model is constructed.The article comprehensively considers the different purposes and decision-making methods of all units in disturbance events.Also,the extreme attack strategy and defense operation during the whole process of disturbance are simulated,and the optimal resilience promotion strategy under the most serious attack is explored.The tri-level problem is equivalent to a bilevel mixed integer linear programming problem using the column and constraint generation algorithm,so that the convergence efficiency and accuracy are improved.Through the design of 22 bus and 50 bus AC/DC system examples,this paper presents the optimal component reinforcement and DG preset strategies,and compares the comprehensive cost and system resilience of different combination plans.Finally,in order to further study the ability of the main components to affect the system resilience.an improved resilience evaluation index system considering the duration of extreme events is proposed.The role of the components in the resilience preparation stage will be fully reflected.On this basis,a tri-level resilience core impact element model is established,and the types of elements participating in the planning or attack process are limited by adjusting parameters.The influence ability of different elements on system resilience are assessed with the improved index system.Through the example,the optimization results in different contrast examples are compared.The converter is determined as the core element type which has the greatest impact on the system resilience.