providing a new characteristic for overcurrent relays

this with the integration of distributed generation (dg) to meshed distribution systems, the operating time of the protective system becomes a major concern in order to avoid nuisance dg tripping. this paper proposes a new tripping characteristic for directional overcurrent relays (docrs) that can achieve a higher possible reduction of overall relays operating time in meshed distribution networks tripping. the proposed tripping characteristic is described in detail. the proposed characteristic is tested on the distribution system is a part of a distribution network, owned by himmerlands elforsyning, in aalborg, denmark. also, in this paper using hybrid algorithm ga and lp for solve relay coordination problem. also, in this paper fault considered is kind of three phase fault. finally, the results of the proposed characteristic compared with a standard iec characteristic. the result shown that propose characteristic are better than standard iec characteristic. therefore, we can use this characteristic for docrs.