Research on the Selection of Short Circuit Impedance of Converter Transformer in Extra-High Voltage

On the basis of analyzing the maximum short circuit current flowing through the converter valve under different short circuit conditions, the authors propose a method of calculating the short circuit impedance. In addition, on the basis of taking the restrictions which have great influence on the short circuit impedance of the converter transformer into account, the authors point out that the short circuit impedance of the converter transformer should be determined by the maximum surge current level which the converter valve withstands. Furthermore, the authors propose the optimization criterion of selecting the short circuit impedance of the converter transformer. After that, according to the optimization criterion, the authors provide an example about the converter transformer in Yunnan-guangdong transmission system, and confirm the reasonable short circuit impedance of the converter transformer should be between 16%~18%.