The Full Form of UPF is‍ Unified Power Format.

Unified Power Format is the popular name of the Institute of Electrical and Electronics Engineers standard for specifying power intent in power optimization of electronic design automation. The IEEE 1801-2009 release of the standard was based on a donation from the Accellera organization.

The Unified Power Format was developed within Accellera and the first version published in 2007. It specifies the power intent of an electronic design and includes elements such as power supply definitions, power control requirements, level shifters, isolation and memory retention. It does not specify how these things are accomplished, only what needs to be accomplished.
The standard was turned over to the IEEE for continued ratification in 2007 and P1801 was formed under the control of the Design Automation Standards Committee (DASC). The first IEEE version was released in 2009.