  This paper proposes an applicable approach to deploy the Coordinative
Real-time Sub-Transmission Volt-Var Control Tool (CReST-VCT), and a holistic
system integration framework considering both the energy management system
(EMS) and distribution system management system (DMS). This provides an
architectural basis and can serve as the implementation guideline of CReST-VCT
and other advanced grid support tools, to co-optimize the operation benefits of
distributed energy resources (DERs) and assets in both transmission and
distribution networks. Potential communication protocols for different physical
domains of a real application is included. Performance and security issues are
also discussed, along with specific considerations for field deployment.
Finally, the paper presents a viable pathway for CReST-VCT and other advanced
grid support tools to be integrated in an open-source standardized-based
platform that supports distribution utilities.
