A Novel Methodology to Estimate the Nonlinear Magnetizing Characteristic of Single-Phase Transformers Using Minimum Information.

This paper presents a novel methodology to estimate the saturation curve parameters of single-phase transformers, using minimum information from inrush and no-load tests. Only the value of the first current peak and the decay time are used from a unique inrush test, and only the third and fifth current harmonics from a unique no-load test. The proposed methodology is based on the existence of a signature for each transformer which can be easily obtained and characterize all possible inrush currents. This is the main contribution of the paper. Different transformers with different parameters have been tested in the laboratory. Experiments and simulations are carried out to validate the methodology. First, the respective no-load and inrush tests are made. Second, the parameters of each transformer are estimated. Third, the performance and accuracy of the proposed methodology are verified by a close agreement between the measured and the estimated saturation curves and between the simulated and the recorded inrush waveforms. Some remarkable advantages of the proposed methodology are: (a) considers the deep saturation, (b) avoids the need to know the residual flux (or to demagnetize the transformer) and the switching angle from the inrush test, and (c) it is computationally straightforward. [ABSTRACT FROM AUTHOR]