On Site Measurement and Simulation of Transferred Lightning Overvoltages Through Power Transformers

High voltage electrical devices such as power transformers are often stressed by the overvoltages that occur during switching operation and atmospheric discharges. Consequently, it is of particular interest to monitor these events in the power network. Nowadays, power transformers can be equipped with transient recorders that measure the voltages at the bushing measurement taps. It is possible to simulate events captured by these recorders, in EMTP. In this process, the crucial element that has to be modelled properly is the power transformer. In this paper, three wideband transformer models are presented: black-box, grey-box and white-box. These models are validated using the transmitted overvoltage measurements at high voltage laboratory. Then, the results of the simulation of the transient event recorded in 220/110 kV substation is presented and compared to the on site measurements results.