Recloser time-current-voltage characteristic for fuse saving in distribution networks with DG

Utilities apply a fuse-saving strategy during auto-reclosing on transient faults. Integration of distribution generation (DG) into distribution networks (DNs) challenges this strategy as the fault current contribution from the DG may lead to the loss of recloser-fuse coordination. This study proposes a relaying scheme to be applied on microprocessor-based reclosers for fuse saving under transient fault conditions. A relay operating characteristic is defined which utilises voltage and current magnitudes at the recloser location. The voltage term in the relay characteristic compensates for the reclosing delay resulting from the DG fault contribution. The main features of the relaying scheme are use of local measurements, i.e. no communication link is required, and its independence of number and location of DG. The proposed relaying scheme is validated by simulation study on a practical 20 kV Iranian DN. It is shown that the new scheme maintains proper recloser-fuse coordination for different fault conditions and DG configurations. Moreover, the maximum DG penetration in different locations is obtained whilst the recloser-fuse coordination is upheld. It is shown in a comparative study that the proposed relaying scheme can maintain the coordination for higher DG penetrations than a recent adaptive method reported in the literature.