This paper is a description of the successful implementation of a model-merge approach for creating and updating the power system model of the new energy management system (EMS) for the China Southern Grid Company (CSG). The power-system model of this new EMS is a merged model of the five models in the five EMS's serving the five province power systems that constitute the China Southern Grid. The merging and the continued updating of the merged model is an automated process. The same process is employed to update the displays in this CSG EMS using updated models from the Province EMS's. All data exchanges are in accordance with CIM, XML, SVG, and TASE2 standards.