Development of test facility for compatibility and performance testing of all-digital protection systems connected to IEC 61850-9-2 standard

The development of intelligent electronic devices (IED) have increased the use of digital protection systems, in which the digitized signals replaced the usage of conventional analog signals. The digitized signals are generated at electronic instrument transformers and they are transferred to protection systems over a process bus based on IEC 61850-9-2 standard. This transferring process between electronic instrument transformers and protection systems requires a detailed performance evaluation, analysis, and compatibility of the two different systems, since various vendors´ instrument transformers and relays are aimed to be connected. This paper presents a developed test facility for all-digital protection system performance evaluations. Typical power system faults are regenerated with the facility and the performance of the digital systems are investigated. The compatibility of an optical current transformer and a digital relay is analyzed. Digital relay´s inverse time delay characteristics are obtained. Results show that all-digital systems provided by different manufacturers can work together and are suitable to protect power systems where protection is needed.