The Study About The Optimization Of Insulation Structure And Grading Ring Of Tap Changer

As one of the indispensable electrical equipments, the performance and quality of tap changer directly affect the safe operation of transformer. Because of the structural design of insulation in switch is unreasonable, the phenomenon of breakdown is frequent when the switch is under high-voltage test by some manufacturers. As a result , while desinging the structure of insulation in tap changer, it is always the key to control the maximum field strength in the high field region.In the first chapter ,the paper described the relevant characteristics of insulation coordination,the factors which brng impacts to both in inner and external insolution. are also listed. Based on a variety of numerical methods, the finite element method is choosed to satisfy the characteristics of insolution media and domain in tap changer.Designing the optimized insulation structure,the two-dimensional (2D) numerical model of three insolution structure ,which around the high-voltage electrode, are established by using ANSYS software.The effect of the oil-gap for improving the electric field distribution on the insulation structure is investigated by changing the parameters of the oil-gap. The simulation results show that the maximum field strength significantly reduced in transformer oil after optimizing the oil-gap and electrode structure, which makes the potential distribution in the tap changer becomes more uniform.In the process of optimizing the parameters of grading ring , The three-dimensional (3D) numerical model of grading ring are established by using ANSOFT software., The effect of the corona ring for improving the electric field distribution on the surface of grading ring is investigated by changing the parameters of the grading ring, such as the ring radius, radius of the ring tube, and the position of the ring in its vertical plane. In addition, based on BP neural network , the mathematical model of insolution structure about grading ring is established .At last, the optimized parameters of the grading ring are obtained.High-voltage test has proved that the above conclusions, which can be applied to related switch products, has great significance and value of engineering applications for ensuring the long-term safy operation of the tap changer in power grids.