An approach to preparing a functional specification for a unified power flow controller (UPFC) using modular multilevel converter (MMC) is documented by this guide. This guide provides the functional requirements for UPFC project application, including UPFC system composition, function and performance requirements, primary equipment requirements, control and protection requirements, characteristic description, spares, engineering studies, testing, documentation, as well as training of UPFC projects. The intention of this document is to serve as a base specification with an informative annex provided to guide utilities, manufacturers, integrators, and other interested entities to apply a particular UPFC project.

This guide provides the functional requirements for unified power flow controller (UPFC) deployment, including application conditions, system architecture, function requirements, performance requirements, primary equipment requirements, control and protection requirements, auxiliary system requirements, testing, spares, and training of UPFC projects, which are suitable for UPFC in transmission power grids.

The purpose of this guide is to specify the functional requirements for UPFC project application, allowing utilities, integrators, and other interested entities to specify the application conditions and system architecture of UPFC, and define the requirements for function, performance, primary equipment, control and protection, commissioning, and testing of UPFC projects. This guide aims to provide the knowledge base, experience, and opportunities for greater utilization of UPFC.