Practical aspects of transformer inrush current calculation using two software packages

Abstract

In the paper, the simulation of the energizing of transformers and more specifically the calculation of inrush currents is dealt with. First, the physical origin of inrush currents is discussed. Then, two different transformers, namely a 20 MVA 10.6/66 kV and a 160 MVA 66/220 kV transformer, are each modelled in two different software packages, namely ATP and DIgSILENT Power Factory. The models are described elaborately and the values of all relevant quantities are given. The models are used to simulate the energizing of the studied transformers from a generator and to investigate the impact of various quantities, such as remanent flux and switching instant. Finally, the simulation results are compared with measurements and it is observed that a satisfactory level of correspondence has been achieved.