High-temperature superconducting (HTS) technology offers an alternative approach to achieve compact transformers, that offer high-efficiency, reduced fire risk power transmission [1-5]. Addressing AC loss is a critical issue in the design of HTS transformers, as it poses -challenge for cooling systems. Numerous numerical studies have been conducted to estimate the AC loss of HTS transformers. However, the impact of iron cores on the AC loss of HTS transformers has been overlooked due to the limitations of simulation methods and computational challenges [6-10]. Recent studies on the AC loss of HTS coil windings coupled with iron cores have shown that the presence of iron cores significantly increases the AC loss in coil windings [11-15]. Therefore, it is necessary to carry out systematic studies to investigate the influence of iron cores on the AC loss of HTS transformers.
In this study, we carried out AC loss simulations for a 3-phase 1 MVA HTS transformer coupled with a three-limb iron core using the 3D T-A homogenization method. The design of the 1 MVA HTS transformer is the same as the HTS transformer demonstrated by Robinson Research institute, Victoria University of Wellington. The high voltage (HV) winding of the 1 MVA HTS transformer comprises 24 double pancake coils (DPCs) per phase wound with 4 mm wide SuperPower wires, while the low voltage (LV) winding employs a 20-turn single-layer solenoid winding per phase wound with 15/5 (15 5 mm-wide strands) Roebel cable. The AC losses of the 1 MVA transformer with and without the three-limb iron core are simulated and compared under various current amplitudes. In addition, magnetic materials with different saturation magnetic fields are considered to investigate their influence on AC loss of the 1 MVA transformer. With the presence of the iron core, flux diverters with different dimensions are arranged near the end of transformer windings, and the simulated AC loss values of the 1 MVA transformer with and without flux diverters are also compared.
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This work was supported by the New Zealand Ministry of Business, Innovation and Employment (MBIE) Strategic Science Investment Fund “Advanced Energy Technology Platforms” under contract No. RTVU2004. Yue Wu acknowledges financial supports from the Chinese Scholarship Council (CSC) and the CSC/Victoria University of Wellington Scholarship.