GPS satellite synchronized test systems recreate fault conditions to troubleshoot protective relay schemes

El Paso Electric had been experiencing misoperations on a segregated phase comparison (SPCU-1A) relay scheme at the Caliente substation (a 345 kV and 115 kV switching station). For faults occurring on the AMRAD to Caliente transmission line, the SPCU schemes for both the AMRAD-Caliente and Newman-Caliente 345 kV transmission lines operated, leaving the east side of El Paso without a 345 kV source. Fault records were taken at the three sites (AMRAD, Newman and Caliente). Composite files were created from the AMRAD and Caliente, and Newman and Caliente waveforms. Hathaway Composite software was used to time-scew, or “line up”, the fault inception at the different substations for each file. These files were then converted to IEEE COMTRADE file format using Hathaway EX-IMPORT software. AVO Multi-Amp PulseMaster software was then used to create test files by adding prefault data and converting waveform magnitudes to secondary values. Portable Global Positioning System (GPS) satellite receivers were used to synchronously begin the automated end-to-end testing of the relay schemes. The synchronous test system was used to provide repeatability in testing and verifying both the AMRAD and Newman protection schemes. Changes were made to peripheral devices (such as current transformers) as well as to jumper locations within the relays. The test files were used to verify the response of the relay schemes to these changes