Integrated AC & DC Design & Analysis
Model-Driven SCADA, EMS, PMS, ADMS & SAS
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The Sequence-of-Operation of protective devices are automatically calculated and listed in an Event Viewer, which is dynamically linked with the one-line diagram. This one-step concept utilizes the intelligent one-line diagram and performs a complete set of actions to determine the operation of all protective devices. The internal shifting (normalizing) of each Time Current Characteristic Curve is based on the individual fault contribution level.
PETRONAS RAPID project is the largest oil & gas refinery and petrochemical plant in Malaysia which is powered by a 1200MW utilities plant and connected to a 275kV Grid supply. The integrated ETAP model for the RAPID complex reached up to 5000 buses that consist of various distribution voltages from 400V up to 275kV. Protection Coordination evaluation study for the RAPID complex was performed using “PD Sequence-of-Operation” to identify abnormal relay behavior, which may not be observed in the conventional TCC curve. When simulating earth fault at 275kV system, there is sympathetic relay operation at all 275kV healthy feeders due to circulating earth fault current. The circulating earth fault current is more than 1pu, which will potentially cause a broader outage to the RAPID complex. Further analysis has been performed by the author and academician experts to ascertain the root cause of the circulating earth fault current. This presentation will discuss the root cause of sympathetic relay operation during 275kV earth fault simulations and the recommended solutions to mitigate the sympathetic operation. This will help engineering design firms and plant operators clearly understand the protection relay behavior during faults by utilizing ETAP special features.