Site acceptance testing of a Duke Energy automation project utilizing a simulation based test approach

As part of a proof of concept for future distribution schemes, Duke Energy has completed the second phase of a project on a distribution system feeder for the Raleigh Central Business District underground system. The feeder consists of two radially operated 12kV underground circuits. Solid dielectric vacuum switches with integrated visible break were installed in nine network vaults during phase 1 of the project. To achieve high electric service availability for the central business district, a communications-assisted, high-speed protection system was developed. Its unique communication architecture utilizes IEC 61850 GOOSE messaging and serial based communications in parallel, enabling the relays to interrupt, isolate and restore power via the nine vault switches once the project is completed. An important aspect of the acceptance test was testing the protection and control scheme. In this scheme 18 relays and two communication technologies are working together as a system. Due to the interdependency of the network protection system and its components, it was critical to test every component as part of a system. Multiple acceptance criteria were defined by describing the initial state of the power system, the incident fault and the expected system state after the interruption, isolation and restoration of the system had taken place. The acceptance criteria were directly configured into the test environment by using a power system model that calculated the test set outputs. A single PC controlled a total of nine test sets, simultaneously injecting all signals according to the selected test case. A requirement for placing the protection system into live operation after installation was the completion of field site acceptance testing. Site acceptance testing included testing the individual switching nodes during commissioning followed by a series of simultaneous network system response testing involving all of the switches. This paper discusses the network installation, site acceptance test planning, testing contingencies discovered during planning, and the outcomes of the site acceptance testing.