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

There is no doubt that superconducting fault current limiters (SFCL) will b e used if their technical and economical benefits are high enough, Up to no w a number of studies have been carried out to show suitable applications o f 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 volt age of 110 kV, lists technical benefits and calculates the economical savin gs. Investigated places in the network are feeder locations of power statio ns, of power station auxiliaries and of local generating units (block-type thermal power stations, wind power stations). Furthermore, coupling locatio ns of networks and busbars as well as the transformer location are investig ated, too, Depending on the location, SFCL either limit the short-circuit c apacity in case of a short-circuit or result in a higher short-circuit capa city during normal conditions without increasing the short-circuit capacity during fault conditions, A high short-circuit capacity improves power qual ity and stability conditions, whereas a limitation of the short-circuit cap acity during fault conditions results in lower strain to other devices. The economical evaluation proposes a method that concentrates on the prospecti ve savings by using SFCL, This is useful because up to now only rough estim ations can be made about the price of SPCL. The savings are set equal to th e costs caused by applying a SFCL, As a result, relative costs (Currency Un it/kW) are obtained, which can be compared with conventional devices for li miting short-circuit currents. In the investigated network it was found tha t feeder locations of power stations and wind generators are the most econo mical places for SPCL.