科研之友
微信
新浪微博
Facebook
分享链接
摘要
Due to the impacts of the core saturation and the filters in AC and DC fields in high voltage direct current (HVDC) systems, the differential protection of the converter transformer may mal-operate during the unloaded transformer energization. On the other hand, in virtue of the particularity of the operating environment of the converter transformer, as the differential current may contain the 2nd order harmonic component with quite high amplitude, the transformer differential protection may fail to trip in the case of asymmetric internal faults. The energizations and internal faults of the converter transformer are simulated and analyzed in this paper. It is disclosed that the 2nd order harmonic restraint criterion is not completely appropriate when it is applied to the differential protection for the converter transformer. According to the investigation of the characteristic of the transformer core, there exists a time difference between the sudden change of phase voltage and the emergence of differential current. Therefore, a novel criterion utilizing the time difference between the superimposed phase voltage and differential current to distinguish between the internal faults and energizations of the converter transformer is proposed. The feasibility and effectiveness of the proposed criterion are validated with numerous EMTDC based simulation tests. ? 2009 Chin. Soc. for Elec. Eng.
- 出版日期2009
- 单位华中科技大学
