Overcurrent relay optimization in a radial distribution network considering different fault locations

Strict protection of the distribution network is critical for the safe and reliable operation of the entire power grid. The solution to the optimization problem of coordinating inverse-time overcurrent relays in a distribution network is usually achieved by minimizing the operating time of primary relays. However, it has not been fully investigated whether the fault location has a significant effect on the solutions. For this purpose, the authors have developed a modified genetic algorithm and tested it on a realistic 15-bus radial distribution system for two different test cases. From the results obtained, it was found that taking fault location into consideration did not actually improve the operation of the overcurrent relays and that using a relatively simple objective function yields better results. In other words, in order to minimize the operating time of protection relays throughout the network, it is only enough to observe faults at the beginning of the protected elements, and include them in the optimization algorithm.