The theory and application of differential protection based on instantaneous values

This paper introduces the new current differential protection based on instantaneous values. Firstly, some theory problems about the novel method are discussed, the operation equation of the protection is presented and its reliability effected by data window is analyzed. The main result obtained is that the width of the data window should be greater than π/2. Then, the paper discusses the special operation character of the novel protection that is called fuzzy zone. Some corresponding conclusions about the above discussion are given. Finally, the paper presents some practical application of the novel protection.