Abstract
In this paper, a lately proposed Harris Hawks Optimizer (HHO) is used to solve the directional overcurrent relays (DOCRs) coordination problem. To the best of the authors’ knowledge, this is the first time HHO is being used in the DOCRs coordination problem. The main inspiration of HHO is the cooperative behavior and chasing style of Harris’ hawks from different directions, based on the dynamic nature of scenarios and escaping patterns of the prey. To test its performances in solving the DOCRs coordination problem, it is adopted in 3-bus, 4-bus, 8-bus, and 9-bus systems, which are formulated by three kinds of optimization models as linear programming (LP), nonlinear programming (NLP), and mixed integer nonlinear programming (MINLP), according to the nature of the design variables. Meanwhile, another lately proposed optimization algorithm named Jaya is also adopted to solve the same problem, and the results are compared with HHO in aspects of objective function value, convergence rate, robustness, and computation efficiency. The comparisons show that the robustness and consistency of HHO is relatively better than Jaya, while Jaya provides faster convergence rate with less CPU time and occasionally more competitive objective function value than HHO.
Highlights
Relay coordination task is considered of great importance for the operation of power systems. e optimal coordination of relays is supposed to guarantee that faults in the protected zones are cleared rstly by the corresponding primary relays, and if they fail, the corresponding backup relays act after a coordination time interval (CTI)
When the directional overcurrent relays (DOCRs) coordination problem is formulated as an linear programming (LP) problem, the value of IP or plug setting (PS) is assumed to be xed; the operating time of each relay (Ti) is calculated as a linear function of time dial setting (TDS)
I 1 where N is the total number of primary relays, Wi is the weight assigned for relay Ri which is equal to 1 for all the relays in this study, and Ti is the operating time of relay Ri calculated by the following 3 kinds of formulations: LP, Nonlinear programming (NLP), and Mixed integer nonlinear programming (MINLP)
Summary
Relay coordination task is considered of great importance for the operation of power systems. e optimal coordination of relays is supposed to guarantee that faults in the protected zones are cleared rstly by the corresponding primary relays, and if they fail, the corresponding backup relays act after a coordination time interval (CTI). Different mathematical models are constructed to mimic different stages of hunts used by Harris’s hawks; a new stochastic metaheuristic algorithm is proposed and designed based on the constructed models to tackle various optimization problems. Another algorithm named Jaya is proposed by Rao in 2016 [24]. Jaya algorithm is used to be compared with the HHO algorithm in solving the DOCRs coordination problem, with the purpose of testing the advantages and disadvantages of each other, according to the objective function value, convergence rate, robustness, and computation efficiency.
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