Study of Short-circuit Faults Affecting Electrical Networks

Most faults in power lines are caused by short circuits resulting from phenomena such as lightning, severe weather, or power surges linked to circuit breaker operations. These short circuits, whether temporary or permanent, require accurate detection and location to enable rapid repair and restoration of power supply. To protect the system against short-circuit currents, which can cause irreversible damage to key equipment, it is essential to quickly disconnect the faulty part of the network. In order to correctly size this equipment, it is essential to estimate the magnitude of the currents likely to flow during a short circuit. This study involved calculating single-phase short-circuit currents in the event of a fault on the Cable, Soluxe, Airoport, Talladje, and Gawaye feeders at the Niamey3 electrical substation. The method used to calculate short-circuit currents in HTB and HTA networks is based on the principle of symmetrical components. This method was chosen for its accuracy and analytical nature. The results obtained show that the Soluxe feeder has the highest short-circuit current, with a value of 1.95 kA, compared to those of the Cable, Airoport, Talladje, and Gawaye feeders, which are 1.86 kA, 0.67 kA, 0.64 kA, and 0.56 kA, respectively. This is explained by the fact that the calculated impedances (direct, inverse, and zero-sequence) of this feeder are lower than those of the other four feeders.