Impact Analysis Of Transformer Magnetizing Characteristics Under DC Bias

As the voltage level to improve, DC bias problem of power transformers increasingly prominent. When the DC current affects the transformer, transformer laminated core magnetization characteristics inside will be affected by magnetic saturation increased.Taking into account the non-linear core and hysteresis and other factors of transformer.This paper selects unified magnetic equivalent circuit model(UMEC) respectively in PSCAD/EMTDC software for different structures transformer simulation study,mainly studing excitation and magnetic properties.during different structures of transformers under the AC excitation and DC bias.Based on the simulation analysis, establishes experimental platform to simulate the direct flow from the power suppl y side and load side of DC bias problem, analysis the excitation and the magnetic properties.Analysis and Calculation of the leakage magnetic field is an important part to support the research DC bias problem.Considering the effect of the leakage magnetic field in the calculation of this study, analysis the leakage magnetic properties, and according to the magnetic field energy method, the leakage inductance of the expressions derived,with getting Rogowski factor; followed by experimental measurement method to quickly and efficiently get the leakage magnetic field parameters.Nonlinear variation characteristic of ferromagnetic mate rials is the fundamental factor affecting the operation of the transformer, to study the influence of magnetic properties of magnetic bias in the calculation of the transformer, improved J-A hysteresis model to simulate transformer magnetic hysteresis characteristics under DC bias conditions. and focus on exploring the effectiveness of the least squares method to extract the parameters of the improved J-A hysteresis model. Then taking the leakage magnetic field and hysteresis characteristics into account to calculate the excitation current, it is proposed to im prove the circuit-magnetic coupling algorithm to analyze characteristics of load excitation transformer under DC bias...