Optimization Of Shed Parameters Of Catenary Polymer Insulators Based On Critical Flashover Voltage Optimization Of Shed Parameters Of Catenary Polymer Insulators Based On Critical Flashover Voltage

As an alternative to ordinary porcelain insulators,the usage of composite insulators in the catenary is increasing with the development of High Speed Railway,which plays an irreplaceable role in improving railway traction power supply systems.However,the excellent anti-pollution performance does not mean that there will be no flashover.In addition,the rapid development of High Speed Railway puts forward higher requirements on the railway power supply system.As an important part of the contact network,the normal operation of composite insulators is the prerequisite for the safe operation of railway power supply systems.Therefore,it is of great significance for improving the reliability of the contact network operation to obtain the pollution flashover voltage accurately and the optimal shed parameters determined.Firstly,the material characteristics of silicone rubber composite insulators are introduced.Taking the flat plate model as an example,the AC critical flashover condition,flashover process and flashover mechanism of composite insulators are analyzed,which provides a theoretical basis for the selection of model inputs.Secondly,based on the data of artificial contamination experiment of contact network composite insulators,four kinds of umbrella parameter are extracted to complete the express of umbrella.A Biogeography-Based Optimization algorithm to optimize the BP neural network is proposed,in which the seven characteristics and ESDD are used as the inputs model,and the flashover voltage are used as the outputs model.Comparing the prediction results with those of traditional methods and test data,the effectiveness of proposed mothed is verified.The prediction value can be adopted as the referential data of the flashover experiments and can efficiently reduce the workload of the pollution flashover experiments.Finally,based on the model,the impacts of the spacing between large sheds S₁,the overhangs of the large sheds P₁ and the difference between overhangs of the large shed and small shed P_d on the 50%flashover voltage characteristics are obtained.The creepage distance and the flashover gradient E_L are taken as the criterion to optimize the parameters of sheds.The results show that,flashover gradient E_L varies regularly with parameters of sheds:spacing between large sheds S₁ and the flashover gradient E_L is a quadratic function;As overhangs of the large sheds P₁ increases,the flashover gradient E_L reaches its maximum value and then decreases;As the difference between overhangs of the large shed and small shed P_d increases,the flashover gradient E_L of insulator first increases and then decreases.By comparative analysis,device parameters for follow-up researches on shed profile optimization of catenary polymer insulators are proposed.