Optimal Overcurrent Relay Coordination in Distribution Networks

Over-current relay coordination plays a critical role
for effective protection of networks since primary protection is
based on over-current detection in distribution systems. Thus,
optimal relay coordination must be ensured between relays
in faulted condition, providing selectivity and fast operation.
Therefore, relay coordination can be designed as an optimization
problem with highly constrained equations in such networks.
Linear programming, which is simple to be implemented and
requires less computation time when compared other optimisation techniques, is widely employed for solving relay coordination
problems. To achieve faster and selective protection a number
of optimisation algorithms have, also, been customised for the
purpose. Water Cycle Algorithm (WCA) is among them and has
promising results, already, depicted in the literature.
However, capacitive currents may jeopardize traditional optimisation process for earth faults. Thus, in this paper, performance
analysis is carried out for earth faults in sample distribution
networks constructed with overhead lines and underground
cables, separately. The results show that in cabled networks,
additional constraints are needed for the optimisation process
to provide selectivity. Consequently, optimal relay settings and
selective protection are ensured by ad