A HYBRID FIREFLY-GENETIC ALGORITHM FOR THE OPTIMAL COORDINATION OF DIRECTIONAL OVERCURRENT RELAYS
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Date
2023-02-19
Authors
Tareq Husam Foqh
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Abstract
Theoretical background: Directional overcurrent relays are applied for power system protection to ensure safe, reliable, and efficient operation. The coordination of directional overcurrent relays is non-linear and highly constrained optimization problem. The main goal of the optimization is to minimize the summation of operating times of primary relays, by setting optimal values for decision variables as time multiplier setting (TMS) and plug setting (PS).
Aims: The main objective of this research is to develop a hybrid optimization algorithm which consists of modified firefly algorithm and genetic algorithm to find better solutions.
Methodology: First, this study modified the original firefly to obtain a global solution by updating the firefly's brightness and to avoid the distance between individual fireflies from being too far. Additionally, the randomized movements were controlled to produce a high convergence rate. Second, the optimization problem is solved using standard genetic algorithm. Finally, the solution obtained from the modified firefly algorithm is used as the initial population for the standard genetic algorithm. The modified firefly algorithm, genetic algorithm and hybrid firefly-genetic algorithm have been tested on IEEE 3-bus, 8-bus, 9-bus and 15-bus networks.
Main Results: The results indicate the effectiveness and superiority of the proposed algorithms in minimizing the overall operating time of primary relays compared to other algorithms mentioned in the literature for directional overcurrent relays coordination.
Conclusion: Compared to modified firefly algorithm and standard genetic algorithm, the proposed hybrid algorithm has minimized coordination interval time between primary and backup relay pairs.
Keywords: Directional overcurrent relays optimization, Hybrid algorithms, Firefly algorithm, Genetic Algorithm.