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  • Development and test in grid of 630 kVA three-phase high temperature superconducting transformer
    Yinshun WANG, Xiang ZHAO, Junjie HAN, Huidong LI, Yin GUAN, Qing BAO, Xi XU, Shaotao DAI, Naihao SONG, Fengyuan ZHANG, Liangzhen LIN, Liye XIAO
    Front Elect Electr Eng Chin, 2009, 4(1): 104-113.   https://doi.org/10.1007/s11460-009-0010-5
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    A 630-kVA 10.5 kV/0.4 kV three-phase high temperature superconducting (HTS) power transformer was successfully developed and tested in a live grid. The windings were wound by hermetic stainless steel-reinforced multi-filamentary Bi2223/Ag tapes. The structures of primary windings are solenoid with insulation and cooling path among layers, and those of secondary windings consist of double-pancakes connected in parallel. Toroidal cryostat is made from electrical insulating glass fiber reinforced plastics (GFRP) materials with room temperature bore for commercial amorphous alloy core with five limbs. Windings are laid in the toroidal cryostat so that the amorphous core operates at room temperature. An insulation technology of double-half wrapping up the Bi2223/Ag tape with Kapton film is used by a winding machine developed by the authors. Fundamental characteristics of the transformer are obtained by standard short-circuit and no-load tests, and it is shown that the transformer meets operating requirements in a live grid.


    • Fig.7 Optimized cross-section of current lead
    Extracts from the Article
    ddz[Ak(T)dTdz]-m˙Icp(T)dTdz+ρ(T)It2A=0,(1)
    where A is cross-section, k( T) denotes thermal conductivity, c p( T) is specific heat, ρ(T) is resistivity, T is the temperature along the lead, I t is transport current, and m˙I is the mass flow rate of the boiled cryogen gas. The optimized cross-section of the current lead is about 60 mm2 by means of simulation. Figure 7 illustrates the test results of heat-leakage with different input losses, which simulates load loss of the transformer, while the abscissa and vertical-coordinate represent simulated load loss and evaporation of liquid nitrogen per hour respectively. The results indicate that the optimum cross-section of the current lead is 64 mm2 close to the simulation. As a result, the cross-section of the LV windings is chosen to be 65 mm2 in the proposed HTS transformer.