Technical and economical benefits of superconducting fault current limiters in power systems

There is no doubt that superconducting fault current limiters (SFCL) will be used if their technical and economical benefits are high enough, Up to now a number of studies have been carried out to show suitable applications of SFCL [1]-[4] but very few reports have been published on their technical and economical benefits in existing networks [5], This paper shows favourable places of SFCL in an urban network up to a voltage of 110 kV, lists technical benefits and calculates the economical savings. Investigated places in the network are feeder locations of power stations, of power station auxiliaries and of local generating units (block-type thermal power stations, wind power stations). Furthermore, coupling locations of networks and busbars as well as the transformer location are investigated, too, Depending on the location, SFCL either limit the short-circuit capacity in case of a short-circuit or result in a higher short-circuit capacity during normal conditions without increasing the short-circuit capacity during fault conditions, A high short-circuit capacity improves power quality and stability conditions, whereas a limitation of the short-circuit capacity during fault conditions results in lower strain to other devices. The economical evaluation proposes a method that concentrates on the prospective savings by using SFCL, This is useful because up to now only rough estimations can be made about the price of SPCL. The savings are set equal to the costs caused by applying a SFCL, As a result, relative costs (Currency Unit/kW) are obtained, which can be compared with conventional devices for limiting short-circuit currents. In the investigated network it was found that feeder locations of power stations and wind generators are the most economical places for SPCL.