A 1 250 kV ·A/10. 5 kV/0. 4 kV three-phase high temperature superconducting ( HTS ) transformer has been designed, integrated, tested and grid-connection demonstrated. The windings of the HTS transformer are made from copper alloy enforced Bi2223/Ag tapes, and the structures of the primary and secondary windings are solenoid and double-pancake, respectively. The three-phase three-limb core is composed of oriented silicon sheet steel, and the cryostat is made of low-temperature resistant glass fiber enforced plastics with room temperature bore. According to the tests, the no-load loss is 2 319. 2 W, the no-load current is 0. 254%, the short-circuit impedance is 5. 6%, and the average load loss is 249 W. Besides, the maximum leakage current between primary and secondary windings is about 12. 6 mA under the power frequency voltage withstand test of 35 kV/1 min/50 Hz, and the negative full wave lighting impulse test with a peak voltage of 75 kV/1. 2 μs/50 μs from the primary winding is carried out. The grid-connection demonstration of the HTS transformer was carried out since September 9th, 2014 and is reliable until now.%对1250 kV·A/10．5 kV/0．4 kV三相高温超导变压器的系统设计、集成、试验与并网示范运行进行了研究。该超导变压器的一次侧绕组为螺线管型,二次侧绕组为饼式线圈结构,均采用Bi2223/Ag铜合金加强高温超导带材制备；铁心为三相三柱式,采用取向硅钢片叠成；低温恒温器带有室温孔,采用耐低温的玻璃钢制作。测试表明,该超导变压器的空载损耗为2319．2 W,空载电流为0．254%,短路阻抗为5．6%,负载损耗为249 W。此外,对一、二次侧之间的主绝缘进行了35 kV/1 min/50 Hz工频耐压测试,测试最大泄漏电流12．6 mA；对一次侧绕组纵绝缘进行了负向75 kV/1．2μs/50μs全波雷电冲击电压测试。完成相关测试后,该超导变压器于2014年9月9日开始并网示范运行,长时间运行可靠。
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