Modeling and Simulation of a Coordinated Power System Protection using Overcurrent Relay
Authors: Nwachi GU, Obi PI, Amako EA, Ezeonye CS
DOI Info: http://doi.org/10.5281/zenodo.6725273
The efficient and reliable operation of a protection system cannot be overemphasized as any shortfall in such system has both huge financial implications and makes the station dangerous and unsafe. The data for the overcurrent relay coordination analysis used in this study was obtained from the Ohiya Umuahia 132/33 kV substation of the Transmission Company of Nigeria (TCN) while the electric transient analyzer program (ETAP) software was used for the analysis. Firstly, a three-phase (3-phase) short circuit test was conducted on the network at the 33 kV busbar. Then, a detailed sequence of operation of the station’s overcurrent relays was done for standard inverse relay setting, very inverse relay setting and extremely inverse relay setting characteristics. Results showed that at t = 0 seconds a 3-phase fault of initial symmetrical current root mean square (RMS) of 3.049 kA, peak value of 7.746 kA and a steady state value of 2.615 kA was induced on the 33 kV busbar, which lasted till t = 0.2 seconds upon action of the circuit breaker. Also, results showed that the individual time current curve (TCC) for the three relays indicated a fault current of 7.746 kA which lasted for 3.57, 3.57 and 3.28 seconds on the network respectively. Effective device coordination of the 132/33 kV transmission station is an appropriate sequence of operation of its protective devices.
Affiliations: Department of Electrical/Electronic Engineering, Michael Okpara University of Agriculture, Umudike, Abia State, Nigeria.
Keywords: Device Coordination, Overcurrent Relay, Protection, Relay Setting, Time-current Curve
Published date: 2022/06/30