Reducing the Impacts of Distributed Generation in Transmission & Distribution Networks Protection Using Fault Current Limiters

Abstract

Increase in power generation capacity of electric power systems has lead toincrease in the fault current level. In some cases fault current levels are exceeding theinterrupting capability of existing transmission and distribution substations circuitbreakers. Since short-circuit currents contain extremely high energy and can damageelectrical equipment, either requires the replacement of a large number of existingsubstation breakers with higher rating breakers or the development of some means tolimit fault current. Different technologies have been employed to design Fault CurrentLimiters FCLs such as turn-off a solid state switch to using superconductors thatrespond with increasing resistance in event of fault current. A proper design ofModular Level Based Solid-State Fault Current Limiters is proposed in this paper,describes the functioning of FCL and the amount of impedance they are required toinsert in series with transmission or distribution substation are discuses. This willallow near instantaneous breaking of bus ties in transmission and distributionsubstations to reduce the available short circuit current and allow existing circuitbreakers to clear at lower fault current levels. Since FCL's are installed in each phaseof the line, the fault is viewed in perspective of per phase. For the purposes of thisstudy, we consider phase to ground fault& phase to phase fault scenarios.