Frequency Domain Modelling of High Voltage Transformers Using a Nonlinear Least Square Estimation Technique

The development of transformer models can be achieved based on experimental frequency response measurements providing access to the windings is available and the physical dimensions are known in order to calculate R, L and C parameter values. Of interest are methods that allow the generation of a suitable model if the R, L and C parameters are unknown and access is restricted to the external terminals of the winding only. Using a lumped parameter model and the measured frequency response across the whole winding, it is possible to estimate the intermediary winding responses. Knowledge of the intermediary winding frequency responses facilitates the development of condition monitoring tools that are capable of locating the source of partial discharge activity or winding deformation within a faulty transformer [1]. This paper includes a full description of the developed modeling technique, along with experimental results from a model winding system that validates the proposed approach.