A New Model for Transformer Saturation Characteristics by Including Hysteresis Loops

The transformer saturation and hysteresis characteristics are important to power systems under transient operations. Conventional methods to determine these characteristics required field test data and several supporting analyses. Due to complicated corelated factors, field tests for such purposes are difficult. Based on a theoretical approach, the transformer saturation and hysteresis characteristics have certain relations with the rms voltage/current relation curve and the current flow through the equivalent core resistor. This paper presents simplified analytical expression in polynomial form to determine the transformer saturation and hysteresis characteristics without field test data. Higher order approximations are simulated for comparison with various capacity transformers. The results are compared with experiments and simulations and show very good agreement. It is possible to determine accurate transformer saturation and hysteresis characteristics with this simplified procedure.