Research On Transformer Differential Protection Base On Positive Sequence Active Power

Existing principles of transformers main protection, especially in criterions of magnetizing rush current, are analyzed deeply in this paper. The author points out questions in existence, and describes a new method based on the sum of positive sequence active power flowing into transformers from each terminal. Firstly, the developing foreground and actuality of power transformer main protection principle are summarized and introduced in detail. Secondly, on the basis of mechanism of the magnetizing rush current, the new protection principle based conversation of energy is pointed out, and its feasibility also is proved in detail. At last, to check the performance of this method, theoretic analysis and digital simulation are adopted.It is confirmed that compared with conventional current differential protection, positive sequence active power differential protection principle is being predominant in distinguishing magnetizing rush current from fault current. Moreover, after adding simple assistant criterions, it can be carried out as independence main protection. Today, it is advocated that two series different main protection principle of main electric equipment may be apply at simultaneity. So it's worth popularizing.