Abstract: The digital acquisition of electrical information provides direct support for the digital substation and even the smart grid. Regarding the characteristics of electronic transformers and merging units, the function module of digital electrical information acquisition is proposed. The influence of the digital acquisition of electrical information on the reliability of relay protection was analyzed from the perspectives of transformer structure, digital transmission, data validation, sampling frequency and system configuration. Moreover, the impact of data synchronization on differential protection was researched. It points out that currently the traditional designing ideas about protection are still mostly adopted in the digital substation relay protection system for the stability of the electronic transformer and the dependency of network communications, and that indepth research and breakthroughs need to be conducted.

Key words: electronic transformer; aircore current transformer; merging unit; relay protection