Study of the phase shifting effects of transformer on fault analysis model of power system

In the conventional fault analysis and calculation method based on the symmetrical components, transformer is often expressed by a leakage reactance model, which ignores phase shifting effects. If the phase shifting effects consideration is needed, the common way is to modify the resulted positive and negative sequence components according to the phase shifting. This method now has been widely used in the traditional fault analysis field. This paper discusses the accuracy of this method. By building two kinds of transformer models, one is the traditional which neglects the phase shifting effects, and the other is the model that considers the actual transformer winding connections (ATP model), the paper calculates the voltages and currents on the two sides of the transformer under various short- circuit faults at different locations. Comparing simulation results on both transformer models shows that there are different errors in voltages and currents under different fault types and fault locations as well. This paper seeks to point out problems with the conventional method, and proposes a potential solution to these problems.