SHEN Zhi-gang, ZHANG Hai-yan. TFR Analysis of Nanqiao Tonverter Cransformer Fault and Proposal for Improving Valve Short Circuit Protection[J]. High voltageapparatus, 2010, 46(6): 98-102.
The valve-side HV bushing(No.2.1) inside the converter transformer
phase C pole Ⅱ in ±500 kV Nanqiao converter station(Shanghai) blasted during operation on Dec.21 2008.By analyzing the TFR diagram
the fault characteristics and its location was deduced and then the fault was found out soon.One defect in valve short circuit protection design was picked up by the analysis which would have the fault escalated while the valve bridge is earthed.To overcome the defect one proposal to improve the logic of the differential current caculation is described which will benefit the projects of Gezhouba-Nanqiao
Three Gorges-Changzhou and three Gorges-Shanghai HVDC links.