Iron Loss and Temperature Rise Analysis of a Transformer Core Considering Vector Magnetic Hysteresis Characteristics...

Area of Science:

• Electrical Engineering
• Materials Science
• Power Systems

Background:

• Direct current (DC) bias from transmission and geomagnetic currents causes abnormal electrical equipment operation.
• Transformer core vector magnetization under DC bias is understudied, leading to inaccurate state estimations.

Purpose of the Study:

• To introduce a dynamic vector hysteresis model for simulating transformer core behavior under DC bias.
• To analyze magnetic properties, iron loss, and temperature distribution in transformer cores.

Main Methods:

• Developed a dynamic vector hysteresis model incorporating rotating and DC-biased fields.
• Simulated a 110 kV single-phase autotransformer core using the model and Finite Element Method (FEM).
• Measured and compared temperature rise with FEM results from the proposed and a standard model.

Main Results:

• Maximum magnetic flux density, coercivity, and iron loss occur at core corners and T-joints.
• Highest temperature increase is observed in the main core limb area.
• The proposed model reduced temperature rise calculation error from ~50-67% to ~4-16% compared to the standard model.

Conclusions:

• The dynamic vector hysteresis model accurately predicts transformer core temperature rise under DC bias.
• This improved accuracy enhances the reliability of power transmission and distribution system state evaluations.
• The model provides a better understanding of transformer core behavior under complex magnetic field conditions.