Real time modeling, simulation and validation of protective relays
AdvisorSrivastava, Anurag K.
Schulz, Noel N.
The protection system plays an important role in the power system to detect the fault, isolate the faulted zone from the un-faulted zone and restore the power supply to the healthy part. In order to validate the developed protection system, hardware in the loop (HIL) tests have been performed on several power system test cases using commercial overcurrent and distance relays from two vendors and a Real Time Digital Simulator (RTDS). Two-bus and eight-bus terrestrial power systems (TPS) as well as a 4-bus shipboard power system (SPS) are developed in RSCAD and used as power system test cases. The simulation results of the HIL tests provides the background to design the software overcurrent relay model, which should have the same functionality as that of the hardware commercial overcurrent relay. The test case power system with the developed software overcurrent relay model is simulated on RTDS for the same fault conditions in the software in the loop (SIL) test. The comparison of the HIL and SIL simulation results was used to validate the software overcurrent relay model. This research work is further extended to implement more complex operations like multiple relay operation and relay coordination using the developed overcurrent relay model. The first step is to conduct the multiple relay operation and relay coordination tests on the SPS and TPS using multiple commercial hardware overcurrent relays. The second step is to modify the RSCAD software overcurrent relay model by adding more functionality to produce the matching results as obtained in the first step for the same test cases under similar fault scenarios. In addition to modeling overcurrent relay, a differential relay was also modeled using LabVIEW. The relay model was tested for different types of fault conditions.