A modified lumped parameter model of distribution transformer winding

The modelling of the distribution transformer winding is the starting point and serves as important basis for the transformer characteristics analysis and the lightning pulse response prediction. A distributed parameters model can depict the winding characteristics accurately, but it requires complex calculations. Lumped parameter model requires less calculations, but its applicable frequency range is not wide. This paper studies the amplitude-frequency characteristics of the lightning wave, compares the transformer modelling methods and finally proposes a modified lumped parameter model, based on the above comparison. The proposed model minimizes the errors provoked by the lumped parameter approximation, and the hyperbolic functions of the distributed parameter model. By this modification it becomes possible to accurately describe the winding characteristics and rapidly obtain the node voltage response. The proposed model can provide theoretical and experimental support to lightning protection of the distribution transformer.