Calculation of Magnetic and Magnetostriction Characteristics of Electrical Steel Sheet Under Harmonic Condition

Studies have shown that the superposition of the third harmonic on the fundamental frequency significantly impacts the magnetic characteristics and magnetostriction behavior of the 3-D wound core transformer. Specifically, as the amplitude, phase, and content of the third harmonic increase, local hysteresis loops emerge in the core's magnetic hysteresis curve, and magnetostriction intensifies. These effects lead to flux distortion, increased losses, and potential risks of local overheating and noise, compromising the stable operation of the transformer. In this context, this article investigates the magnetic and magnetostriction characteristics of a 3-D wound core transformer (380/220 V/50 kVA) under the influence of fundamental and zero-sequence harmonics. A mathematical model combining the Everett, Mayergoyz, and Preisach (EMP) approaches is proposed to describe the magnetic and magnetostriction properties. The research examines the impact of third harmonic content and phase on the magnetic and magnetostriction characteristics of the transformer core's electrical steel (grade: 20SQG090). Experiments were conducted to analyze these characteristics under varying harmonic content and phase conditions. The study provides curves depicting the magnetic properties, magnetostriction behavior, and losses of 20SQG090 oriented electrical steel for different harmonic scenarios, laying the foundation for further investigation into transformer vibration considering magnetostriction effects.