Analysis And Evaluation On The Vulnerability Of The Integrated Shipboard Power System Topology

The power supply reliability and power quality of the shipboard power system are directly related to the ship's life safety and mission tasks.However,the working environment of the shipboard power system is usually very bad.So,It's quite difficult to maintain the high power supply reliability.Because the topological structure of the ship power network has a great influence on the stability of the power system,and it is the key factor to determine the reliability of the shipboard power system.Therefore,it is necessary to analyze and evaluate the vulnerability of its topology structure and identify the fragile links.The vulnerability of the power system can be divided into structural vulnerability and state vulnerability,And complex network theory is a powerful tool to study the frangibility of power system.Based on the theory of complex network,this paper studies the structural frangibility of ship power system.This paper introduces the characteristic parameters of the power system vulnerability based on the complex network theory,4 basic network models and their important features,as well as the characteristics of the small world and the scale-free.And based on the traditional complex network theory,the topology model of three typical ship power grids with radiation structure,ring structure and band structure is set up.The degree,degree distribution,eharacteristic path length and clustering coefficient are studied,and the topological characteristics of the 3 kinds of ship power system structures are compared and analyzed.In order to further evaluate the robustness of the three power grid structures to single line removal attacks,the network redundancy is compared and analyzed in this paper.A typical four power station ring ship power grid is taken as an example to establish a weighted topological structure model.And the method of node degree and node number,the cumulative probability distribution of node degree and the cumulative probability distribution of node number are used to study the scale-free characteristics of the network.On the basis of fully considering the load characteristics of the ship,an improved electric betweenness index is proposed,the fragile components of the ship power grid are identified,and the post fault evaluation index system is proposed,and the static analysis method is used to verify the identification results.Then,taking the hybrid power system of AC and DC as the research model,an undirected graph model is established.Based on the complex network theory and adopting the method of cascading failure simulation,the structural vulnerability of the power system is analyzed and evaluated by using the percentage of the largest connected components,the percentage of the load loss and the percentage of transmission efficiency decreasing as the performance evaluation index of the network after the fault.Finally,the computer simulation of the typical shipboard power system is established by PowerFactory.By observing the change curve of the power angle of the generator rotor,the correctness of the identification results of this paper is verified.