The use of fault current limiter to reduce the operating time of relays

Abstract

In distribution network with displacement at network level, the fault current does not significantly change and it is not possible to effectively utilize the inverse time over-current relays, since, if the number of primary and backup relays increases, we are faced with problem of time accumulation in the operating of upstream relays. In this paper, using fault current limiter (FCL) along feeder, the problem of the time accumulation has been solved. This is done considering that by reducing the Time Setting Multiplier (TSM) of a relay (while the fault current is not changed), the operating time of the relay is reduced. According to the impact of the location and size of the FCL on the operating time of relays, different scenarios have been studied to find the suitable location and size of FCL. The simulation results show that if the right location and size of FCL are selected, large reduction in operating time of the relays will occur. Simulations have been done in Digsilent software and with its DPL programming.

Keywords

• inverse time over-current relays
• time accumulation
• fault current limiter
• digsilent software