In this article the development of air core current limiting reactor provided with controller is proposed to be used in AC fault current limitation of low and medium voltages. It contains an air core transformer, which its primary winding is connected in series with the mainstream of the electrical radial network AC system whereas the reactor secondary winding is fed from the secondary winding of voltage transformer stepped down from the network voltage, which is 11 kV in the case under study. The radial distribution electrical network is protected by a circuit breaker in series with the limiter for interrupting the fault after the air core reactor has been succeeded in limiting the fault current. The performance of the proposed air core current limiting reactor is investigated under various parameters such as varying the mutual inductance with fixed self- inductance and varying the mutual inductance at different values of self-inductances. Additionally, the effect of fault resistance on the fault current has been discussed. Furthermore, the study of air core current limiting reactor is done under different short circuit faults such as single line-to-ground, double lines-to-ground and three lines-to-ground. A comparison of the complete system performance is done with and without air core reactor concerning the re-striking voltage of the circuit breaker and the fault current which is the primary current of the reactor. The new Air Core Current Limiter has advantages over the other current limiters because it does not contain non-linear devices that may cause harmonic problems in the network. It can also be used in different voltages. It does not depend on charging capacitors in its feed, which improves its continuity in operation. Unlike the structures of FCLs, the new Air Core Current Limiter doesn't use DC power circuit or power electronic components such as diodes or thyristors. This minimizes the distortions and power losses may result from using such these elements. |
