Simulation Of Transformers Tolerance Ability Of DC Bias

DC bias invasion of transformer windings will not only cause vibration, noise and temperature of transformer core and so on, the system will be produced a series of serious impact. Carry out the transformer DC bias influence quantificational is of great significance on the safe operation of power systems. This paper establish a detailed model of the transformer with the coupled electromagnetic method, which including the main magnetic flux leakage circuit. On the basis of the validation of the transformer model, calculated the winding current changes of power transformer(include single-phase three-limb, three-phase three-limb and three-phase five-limb transformers) in different magnetic bias cases and in the transformer no-load and load cases, then combined with two-dimensional finite element software ANSYS quantitative analysis of the internal magnetic field variation of transformers. Finally use transformer-related empirical formula to evaluate the noise increases of these three kinds of power transformers at various DC bias. This paper provided a certain amount of data basis to assess the tolerance of these three kinds of transformers' capacity of DC Bias.