Field experience and assessment of GPS signal receiving and distribution system for synchronizing power system protection, control and monitoring

This paper describes the field experience and assessment of a GPS signal receiving and distribution system for synchronizing power system protection, control and monitoring. Application of GPS synchronization to protection, control and monitoring systems is becoming more popular in the field of power systems. However, the actual performance and reliability of GPS signal receipt within the substation environment has not been comprehensively assessed. This paper includes the system configuration for GPS synchronization, the results of our assessment of GPS synchronizing signal receipt in terms of performance and reliability. The authors introduce several techniques for reliably applying GPS synchronization to power system protection, control and monitoring especially in the event of GPS signal loss or failure. A T-RAIM, (time receiver autonomous integrity monitoring) function has been tested and the ability to maintain synchronizing signal stability was observed when a satellite anomaly occurred in January 2004. The actual service experience of a GPS based line current differential relay developed by the authors and now in commercial operation in Europe are described in this paper.