Distribuição de correntes de curto-circuito e fenômenos de indução em linhas de transmissão

Abstract

The calculation of the distribution fault currents in ground wires of transmission lines (TLs) is essential for proper sizing of ground wires, insulators and fittings of composing arrangements of LTs. ANEEL, in recent auctions of TLs, has defined very high levels of fault currents in the substation, on the order of 50 kA, impacting greatly the design of the components of the TLs. The level of fault currents is not the same throughout the TL, being larger nearby substations and tending to stabilize after a few spans. Thus, it is very important to know the distribution of these currents in order not to overstate the components of TL and therefore represent a high economy for the project. The knowledge of the fault current in each tower of TL is also important for the design of grounding systems. In certain locations accessible to people, it is necessary that the overvoltages established in the soil do not exceed the safety limits prescribed by standards. Also regarding the proper sizing of the components of TL, it is also important to observe induction phenomena associated with alternating voltages of the system. ANEEL establishes a loss limit to the ground wires of TLs (maximum 5% loss of power conductors). Thus, it is important to evaluate the induced currents in ground wires. The software ATP (Alternative Transients Program) will be used for this assessment, as well as for the verification of other problems with induction in TLs. In this respect, this work of completing the Specialization Course in Electrical Power Systems will present a methodology for calculating fault currents distributed along TLs, based on published references on this subject in the IEEE. One goal of this work is also a development of software for the calculation of these currents. Moreover, to evaluate some cases problems with induced voltages in circuits near the LTs by ATP.