Load frequency control is among the most important control tasks in power systems operation. Many researchers have focused on tuning the load frequency controllers using single-objective evolutionary algorithms. To av...
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Load frequency control is among the most important control tasks in power systems operation. Many researchers have focused on tuning the load frequency controllers using single-objective evolutionary algorithms. To avoid the drawbacks of single-objective optimisation algorithms, in this paper, tuning the load frequency controllers is modelled as a many-objective (MO) minimization problem. This MO optimisation problem is solved using an MO optimisationalgorithm with clustering-based selection. Considering the maximum value of each objective among the non-dominated solutions found by the MO optimisationalgorithm, the worst solution is determined. To select one of the obtained non-dominated solutions as the controllers' parameters, a strategy based on the maximum distance from the worst solution is proposed. In order to measure the effectiveness of the proposed MO technique against several recently proposed single-objective optimisation algorithms, for tuning load frequency controllers, comparative simulation studies are carried out on two different test systems. Simulation results show that, in terms of different performance indices, the controllers designed by the proposed MO method are far superior to the controllers designed with the single-objective optimisation algorithms. Also, the presented results confirm the robustness of the controllers designed by the proposed method in case of power system parameters variations.
The minimisation of discrimination time between main and backup overcurrent (OC) relays is one of the most important issues in power system relays coordination. On account of the massive computation burden and complex...
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The minimisation of discrimination time between main and backup overcurrent (OC) relays is one of the most important issues in power system relays coordination. On account of the massive computation burden and complexities for determining power system breakpoint, the implementation of the previously reported OC protection methods in large interconnected networks is almost impossible or at least cumbersome. In this regard, a variety of optimisationalgorithms have been presented for coordination between relays and finding optimal operation time (OT) of the protection system. The previously reported single-objective optimisation algorithms have some limitations/drawbacks regarding OT of relays and their coordination. In this study, a new multi-objectiveoptimisationalgorithm is presented for coordination of OC relays in interconnected networks, based on multi-objective particle swarm optimisation (MOPSO) and fuzzy decision-making tool (FDMT). Then, using some useful assumption and recommendations of IEC-6090 and fault calculations for the microgrids including distributed energy resources, the proposed method is generalised for OC relay coordination in microgrids. Finally, the proposed method has been successfully implemented on different test systems and the obtained results have been compared with other reported methods to prove accuracy, authenticity, and efficiency of the MOPSO/FDMT-based protection and relay coordination algorithm.
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