An Improved Mathematical Model using PSO for Estimating Polarization Parameters of Power Transformer Oil-Paper Insulation with FDS data

The life of a transformer is associated with the state of the insulation system, one of the techniques used to measure the insulation system is frequency-domain spectroscopy (FDS), which measures the dielectric properties in the frequency domain. This work establishes a mathematical model with the data of the FDS to estimate the parameters of the equivalent circuit of the dielectric response of the paper-oil isolation system of the transformer, which is a group of non-linear equations that make its resolution complex. The equations are transformed into an optimization problem using the least squares technique, and using the Particle Swarm Optimization (PSO) to solve them. In order to test the efficiency of the proposed method, the parameters of the electrical circuit of the isolation system in two transformers were estimated and the curves of the dissipation factor (tanδ) were compared with the values obtained by the measured by the FDS method. The relative error obtained between the measured and calculated curves was less than 0.8%, which means that the proposed method for estimating the parameters of the dielectric circuit equivalent to the oil-paper insulation system is valid.

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