Research On Ultrasonic Localization Of Partial Discharge In Power Transformer Based On Improved PSO Algorithm

Large power transformer as an important equipment in power system,the insulation condition of which has a significant impact for the reliable operation of power system.Partial discharge of transformer is one of the important reasons leading to insulation degradation.Therefore,domestic and foreign scholars have done lots of research about partial discharge within transformer,Ultrasonic localization method was a simple and practical localization method,which can be used for more serious electromagnetic interference occasions,and can realize real-time positioning detect,it has been developed rapidly in recent years.Particle Swarm Optimization was a new swarm intelligence technique which proposed by Kenney and Eberhart in 1995.It was an adaptive random algorithm based on population search strategy, Because of its simple,few parameters,easy programming features,it has been widely used in engineering practice,Such as function optimization,neural network training,system design,power and chemical industry.In order to research and realize PD sources localization within power transformer and to improve the accuracy of localization,The major works of this thesis are in the several aspects as follows:First,the particle swarm optimization algorithm was researched in this thesis.To overcome shortcomings of basic particle swarm algorithm that easy fall into local minimum and low searching accuracy,the improved PSO algorithm with chaos searching was designed by combining the basic particle swarm algorithm with chaos searching and the effectiveness was verified.Second,the mechanism of partial discharge generated ultrasonic wave was studied,the general rule of air-bubble PD model generated ultrasonic waves was analyzed. And the ultrasonic wave detecting system was set up. On this system, the frequency distribution of ultrasonic wave excited by variant PD model and the propagation of ultrasonic wave in the transformer can be researched,These provided reliable theory for ultrasonic location.Then,the mathematical model of ultrasonic localization of partial discharge in power transformer was designed based on principle of geometric localization.The model was transformed to a constrained optimizing problem and the PSO algorithm with chaos searching was applied to the optimized process of ultrasonic positioning.Finally,the delay value of ultrasonic propagation was obtained by the system and simulated by computer program.The improved PSO algorithm used to ultrasonic localization is feasible.