Simulation Study On The Influence Of Converter Transformer Temperature And Geometric Sizes For Main Insulation Electric Field

The converter transformer is one of the necessary equipment in HVDC transmission system,and its reliability is critical to entire transmission system.In the operation process,converter transformer must be burdened the effect of AC voltage,DC voltage and instantaneous polarity reversal voltage,the problem of electrical insulation is more pronounced.Due to the vast territory of China,the temperature of the north and south is very different.Inevitably,the converter transformer needs to operate at different temperatures.In order to ensure the normal operation of the converter transformer,the change of main insulation electric field at different temperatures needs to be considered.At the same time,in order to ensure converter transformer has better insulation performance,it is necessary to analyze the main insulation electric field of converter transformer of different geometrical sizes,which provides application conclusions for product design.Firstly,under this background,2D and 3D simplified calculation models of a typical converter transformer body are established and simulated by using finite element analysis software Elec Net.2D simulation results and 3D simulation results are compared and analyzed.Secondly,on the basis of analyzing the influence of temperature on dielectric parameters of transformer insulation material,converter transformer models at different temperatures are calculated and analyzed.The distribution rules of AC electric field,DC electric field and DC polarity reversal electric field of converter transformer at different temperatures are obtained.In this thesis,the main insulation electric field of converter transformer body with different geometric sizes is simulated and analyzed.The influence factors such as the curvature radius of electrostatic ring,the number and curvature radius of angle ring and the distance of main insulation and longitudinal insulation are considered.At the same time,influence of anisotropy and nonlinearity of insulating materials on the main insulation electric field are also investigated.The simulation results are analyzed,which provides the reference for the structural design of converter transformer.In the end,the distribution of AC electric field,DC electric field and DC polarity reversal electric field of valve side bushing of a typical converter transformer is simulated.The insulation margin is calculated,and the weak position of insulation is obtained,which provides the basis for insulation design of the converter transformer bushing and the establishment of relevant standards.