CRITERIA AND DEVELOPMENT TREND TO IDENTIFY INRUSH CURRENT OF POWER TRANSFORMERS
Ge Baoming 1, Wang Xiangheng 2, Su Pengsheng 2, Wang Weijian 2 (1. Northern Jiaotong University, Beijing 100044, China; 2. Tsinghua University, Beijing 100084, China)
Distinguishing magnetizing inrush currents from internal faults has been a key problem of the power transformer differential protection. Many methods have been proposed for this purpose around the world, but they have not yet fulfilled the requirements of power transformer relay protection, including dependability (no missing operation), security (no false tripping), and speed of operation (short fault clearing time). This paper focuses on the detailed analyses and evaluations for all kinds of the proposed methods, such as their principles, advantages and disadvantages, key technologies, state of arts on their studies and applications. Furthermore, the prescient methods used for distinguishing magnetizing inrush currents from internal faults are proposed through extensive studies.