On-Site Test of Differential Protection for UHV Transformers

The 1 000 kV transformers of Southeast Shanxi substation consists of the main transformer, the compensation transformer and the voltage regulation transformer, the single active part structure is applied to the latter two and they are mutually independent of main transformer. The polarity requirement of the differential protection for the 1 000 kV transformer is special, not only the different polarity requirements of differential protection has to be satisfied while one TA winding is shared by two kinds of differential protections for compensation transformer and voltage regulation transformer, but also the polarity change of current caused by positive and reverse voltage regulation has to be solved. In this paper, the differential protections for compensation transformer and voltage regulation transformer of 1 000 kV transformer are configured, the polarity of TA winding for differential protection of compensation transformer and voltage regulation transformer is analyzed, and the on-site test method for differential protection of compensation transformer and voltage regulation transformer is researched. Test results show that the special structure applied to 1 000 kV transformer can meet the special polarity requirement of TA for differential protection of this 1000kV transformer.