Experience of transformer´s inrush current modeling for the purposes of relay protection

In case of transformer failure there is a high risk of losing part of power system, which can result in disruption for consumer power supply. This is main reason for power transformer protection requirement to be so high. Power transformer is a complicated object considering its protection. Sensitivity level is a key element in inter-winding faults detection. Our idea is in creating an additional function that will use an inrush current surge as an information source for inter-winding fault detection within transformers. However it is absolutely impossible to perform multiple tests with real megawatt class transformer. That is the key why it is so important to make a correct model and to be sure that model is identical to real transformer. We choose Matlab+Symulink+Symscape+SymPowerSystem combination as modeling environment, we have tried multiple environments and selected this one as best performing. To verify our model we use measured data from small test transformer.