Abstract:
Connection of distributed generation (DGs) powered by renewable energy resources in
power systems has numerous benefits. However the presence of these (DGs) increase
the fault current levels in different points, and disturb the protection coordination of the
existing relays. Two approaches are proposed for coordination of directional overcurrent
relays (DOCRs) in power systems with (DGs), depending on the types of system relays
either adaptive or non adaptive.
For adaptive protection system, the first proposed approach is based on linear
programming technique which used to calculate the relay settings in case of DGs
existing or not. For non-adaptive protection system, the second proposed approach is
introduced, in which minimum impedance of fault current limiter is calculated to restore
the coordination of relays without altering the original relay settings. The two proposed
approaches are implemented and tested on IEEE-39 bus test system.