Research on Retrofitting Scheme of Merging Unit and Intelligent Terminal in 500kV Smart Substation

At present, many of the merging units and intelligent terminals used in smart substations that in operation in China are defective and unqualified products, bringing security hidden troubles to power grid. So It is urgently needed to replace them with qualified equipments which through professional testing. Nowadays, power users are demanding higher and higher reliability of power supply, so it is quite necessary to carry out retrofitting under the minimum outage mode, 500kV substation in particular, the retrofitting by large area outage is nearly impossible. Regarding this, the article combines the retrofitting situation of merging unit and intelligent terminal in 500kV smart substation, and studies the safe and feasible minimum blackout mode and the security risk under this mode, meanwhile, puts forward the principles and schemes of implementing security measures for these security risks.