Fault Analysis of Nigerian 330kV Power System

Abstract

This work involved the study and simulation of various faults, (single line-to-Ground fault L-G, line-to-line fault L-L, 3phase Balanced fault L-L-L, and Double line-to-Ground L-L-G) in the Nigeria 330kV power network system and the analysis of results. Data from Power Holding Company of Nigeria (PHCN), National Integrated Power Projects (NIPP), now Niger Delta Power Holding Company of Nigeria (NDPHCN), and Independent Power Producers (IPP) between September 2009 and December 2012 were collected and processed. The Network was then modelled in both ETAP 4.0 Transient Analysers and Power World Simulator (PWS) 8.0 Environment using Symmetrical Components equation and Newton-Raphson Power Flow algorithm. The essence of this model is to determine the time limit of transient fault, before, during, and after 3phase fault occurrences in the largest generating station (Egbin) in the network. Results obtained indicate that there were some weak bus voltages outside the statutory limits of (0.95p.u.-1.05p.u.). These include: Gombe, Jos, Kaduna, Kano, Shiroro, Abuja (Katampe), Sapele, and National Control Centre. Total load in the system was 3000MW+j000.00 MVAR and total generation was 3029.9+j3408MVAR.  Power losses from the existing generating stations and transmission lines were 29.9MW-j3408MVAR from September 2009 to December2011.Total load in the system was 3496.589MW-j2869.397MVAR, and total generation was 4328.543-j335.777MVAR. Power losses from existing generating stations and transmission lines were 831.942MW - j066.000MVAR from December 2011 to December 2012.Results obtained from ETAP and PWS, showed that the most severe fault is that of 3phase balanced fault and the highest fault current is that of line-to-ground fault. The actual value of fault current is dependent on the number of generating plants actually in service at the time the fault occurs.