Research on transmission lines multi current differential relay scheme

As two form of differential protection applied dominantly, phasor value based differential protection is easily influenced by current transformer saturation, and sampled value based differential protection must improve the performance response to slight internal faults. In this paper, multi different protection which combines phasor value based differential protection with sampled value based differential protection is proposed. In such scheme, the shortcoming of each differential theory is overcome and the merits are compensatory each other. The result of EMTP/ATP digital simulation indicates that the proposed scheme advances greatly the performances of differential protection for transmission line such as reliability, sensitiveness, trip speed and immunity to current transformer saturation. Especially the algorithm and logic of the proposed scheme are easily and experientially, so it can be suit for project application well.