9Guzman A, Zocholl S, Benmouyal G, et al. A current-based solution for transformer differential protection-part Ⅰ: problem statement [J]. IEEE Trans. Power Delivery, 2001, 16(10): 485-491.
10Keizo Inagaki, Masaru Higaki, Yoshiaki Matsui, et al. Digital protection method for power transformers based on an equivalent circuit composed of inverse inductance[J]. IEEE Trans. on Power Delivery, 1988, 3(4): 1501-1510.