Identification Technology of Excitation Inrush Current in Power Transformers Based on Calculated Electromotive Force

This article proposes method for identifying inrush current in transformers based on calculating electromotive force. By comparing high-voltage side bus voltage with the calculated electromotive force, it is determined whether the transformer has experienced excitation inrush current. The first section of this article elaborates on the significance and current research status of identifying excitation inrush current technology; Section 2 analyzed main magnetic field of transformers and provided the definition and calculation method for calculating electromotive force. Section 3 analyzed the differences in the electrical circuit of transformers when they experience excitation inrush current and internal faults, and explored the differences between the high voltage side bus voltage and calculated electromotive force in the two scenarios based on the specific situations of excitation inrush current and internal faults. Section 4 proposes the calculation formula for converting the full component of the current on the delta side of the transformer to the star side, and based on this, summarizes action logic of transformer differential protection using an excitation inrush current identification method based on calculated electromotive force. Concentrated parameter circuit technology was used to simulate and verify the rationality of the method under three working conditions: air charging surge, fault within the operating time zone, and fault within the air charging time zone. Section 6 provides a summary of the entire text.