Simulation study of DC bias enduring ability of 500 kV power transformer

In order to further study the DC bias enduring ability of 500 kV power transformer, DC bias simulation model of 500 kV auto-transformer is built based on the electric circuit and magnetic circuit combined model according to the J-A hysteresis loop theory. The effects of magnetizing property of silicon steel sheet including coercive force, remanence, hysteresis loss to the enduring ability of 500 kV power transformer are simulated through the variations of key parameters in J-A model. It is seen that the magnetic currents are distorted with the occurrence of even harmonics when the DC component enters into the power transformer. The magnetizing currents are increased with different amplitudes with the increasing of DC component. When the coercive force of hysteresis loop is increased, the variations of magnetic currents and its total harmonics distortion are increased gradually. When remanence and hysteresis loss are increased, the variations of magnetic currents and its total harmonics distortion are increase