Study on Consideration of Critical Clearing Time inOvercurrent Relays Coordination in Presence of FaultCurrent Limiter and Distributed Generation

In presentation of distributed generations indistribution networks, there are concerns about coordination ofprotection facilities such as overcurrent relays. Indeed,occurrence of short circuit causes severe changes in powerelectric, power angle, and consequently the speed of synchronousgenerator that if these disturbances aren’t eliminated beforereaching critical clearing time, synchronous generator is out ofsynchronism with the network. In this paper, for creatingcoordination among overcurrent relays at the instant ofoccurrence of fault and improvement of transient stability of thepower system, a resistive superconducting fault current limiter(RSFCL) is used, and the optimal selection of this type of faultcurrent limiters has been done, using genetic algorithm. For thispurpose, an objective function is defined so that in addition toselection of minimum value for the size of fault current limiterand satisfying the purpose of decreasing costs, the summation ofcoordinated operating time of relays for different faults willreach minimum possible value. Also, this objective functionselects the size of fault current limiter using Equal Area Criterionso that critical clearing time according to different locations offaults will be at maximum possible value.

کلیدواژه ها:

Distributed generation ، Transient Stability ، Synchronous generator ، Fault current limiter