Modeling and Testing of Protection Relay IED

The analysis of protection relay operation is very important in order to determine the cause of unexpected behavior of the relay. This is useful in identifying problems with the relay settings or with the implemented protection algorithm that may result in an undesired operation and system disturbances. If the conclusion is that the relay IEDs did not operate as expected, the user may change the settings and test the relay by replaying the recorded fault waveform through a test device to check the performance. The process of analysis is complicated and requires special equipment, as well as a relay IED to implement the modifications and to test the new configuration. The main objective of this paper is to test and verify the performance of a protection relay IED through off-line and on-line tests. The results show that these testing tools are very useful during the commissioning and operation of a protection relay IED.