In view of such issue as difficult development of periodic detection on the accuracy of power quality monitoring device installed in the substation and operated for many years in substation，the energy industry standard

Technical Specification for Online Comparison of Power Quality Monitoring Device

is interpreted in this paper. In this standard，the specific scope of application is defined，the common architecture of the power quality comparison measurement device is designed，the basic requirements for each component module of the power quality comparison measurement device is given，the on-site periodic detection method applicable to the online power quality monitoring device is proposed，the online detection process is formulated and the specific detection data processing requirements and methods are given.