The correction of instrument transformer ferroresonance model in IEC standard and study on resonance interval based on transformer damping

Abstract

The traditional ferromagnetic resonance model of the inductive voltage transformer in the IEC/TR 61869-102 transformer standard ignores the DC resistance of the transformer. The author believes that ignoring the damping effect of the transformer itself is not justified. Based on this, the model is modified, and the corresponding differential equation is derived. Through simulation and field testing, it is found that the DC resistance of the transformer has a damping effect on resonant overvoltage and resonant overcurrent. Moreover, with an increase in DC resistance, the ferromagnetic resonance region decreases. By increasing the DC resistance of the voltage transformer, it helps to reduce the ferromagnetic resonance interval as well as the inrush current.