Short-circuit impedance design for converter transformer of superconducting magnet power supply for CRAFT
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摘要: 聚变堆主机关键系统综合研究设施(CRAFT)超导磁体电源兼具大电流稳态运行、高功率脉冲运行和瞬态故障抑制能力的需求。换流变压器的短路阻抗与超导磁体电源的特性密切相关。为了优化超导磁体电源的性能,基于交直流系统的参数和换流变压器的等效电路模型,研究了换流变压器短路阻抗与超导磁体电源的输出电压、谐波电流、短路故障电流和无功损耗的关系。短路阻抗越小,超导磁体电源的额定输出电压越高,无功损耗越小,这些特性对CRAFT超导磁体电源的性能有利,但是短路故障电流和谐波电流增加,影响电源的短路故障抑制能力和谐波特性。在CRAFT超导磁体电源换流变压器短路阻抗设计时,首先短路阻抗必须满足直流电源的额定输出电压和故障电流抑制能力,其次,由于CRAFT超导磁体电源是多相变流器,仅产生高次特征谐波电流,含量少便于抑制,因而尽量选择较小的短路阻抗。
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关键词:
- 聚变堆主机关键系统综合研究设施 /
- 电源 /
- 短路阻抗 /
- 谐波电流 /
- 无功功率
Abstract: The superconducting magnet power supply for the Comprehensive Research Facility for Fusion Technology (CRAFT) has the abilities of large current steady-state operation, high power pulse operation and transient fault suppression, which is closely related to the short circuit impedance of converter transformer. On the basis of parameters of AC system and equivalent circuit model of converter transformer, the relationship between the performance of superconducting magnet power supply and the short circuit impedance of converter transformer is studied. The research shows that the small short circuit impedance is beneficial to the output voltage and the reactive power loss of superconducting magnet power supply, but the short-circuit fault current and harmonic current increase accordingly. For short-circuit impedance design for converter transformer purposes, firstly, short-circuit impedance must satisfy the transient fault suppression capability and the rated output voltage, and secondly, it is easy to suppress the high characteristic harmonic current brought by thyristor multi-phase converter for CRAFT, hence small short-circuit impedance should be chosen.-
Key words:
- CRAFT /
- power supply /
- short-circuit impedance /
- harmonic current /
- reactive power
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表 1 超导磁体电源系统基本参数和性能指标
Table 1. Design parameters and performance of the power supply
rated voltage/V rated power/MW rated voltage/kV rated current/kA maximum output pulse current/kA pulse width/ms 250 30 0.25 120 400 200 表 2 主要设备的电气参数
Table 2. Electrical parameters of main equipments
parameter rated
voltage/kVshort-circuit
capacity/MVArated
power/MWtransformer
ratioshort-circuit
impedanceload loss/
kWresistance/
mΩinductance/
mΩpower grid 110 1270 − − − − − − step-down transformer − − 63 110/35 10.5% 232 − − power cable − − − − − − 239.4 110.6 converter transformer − − 8 35/0.197 − 46 − − AC busbar − − − − − − − 0.314 表 3 主要设备的等效阻抗
Table 3. Equivalent impedance of main equipments
parameters equivalent reactance/μΩ equivalent resistance/μΩ power grid 30.6 3.1 step-down transformer 65 2.3 power cable 3.5 7.6 converter transformer − 27.9 AC busbar 314 0 -
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