An Enhanced High‐Frequency UMEC Model of Power Transformers Considering Capacitive–Inductive Coupling

ABSTRACT

With the large‐scale integration of renewable energy and widespread deployment of power electronic devices, high‐frequency harmonics have become increasingly prevalent in power systems, which renders the impact of distributed capacitance on power transformers a critical concern for power system operation. Conventional high‐frequency models of transformer fail to adequately consider the combined effects of core saturation and distributed capacitance. This study proposes a capacitance conversion method based on the duality principle, thus establishing an enhanced unified magnetic circuit model for power transformers. The methodology references the nonlinear excitation inductance fitting approach derived from air‐core inductance to efficiently compute reluctance. The study proposes a distributed capacitance fitting function derived from transformer design procedure, which enables rapid and accurate capacitance computation. The enhanced and conventional models are developed using C++ programming and compared with the measurement results of transformer entities. Results indicate that the enhanced model more accurately characterises capacitive–inductive coupling interactions. This model provides a reliable theoretical tool for the high‐frequency transient analysis of power transformers.