Coordination of overcurrent relays is one of the most challenging issues in the field of power systems operation. Since this issue is a complex and highly-constrained optimization problem, thus, the definition of appr...
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Coordination of overcurrent relays is one of the most challenging issues in the field of power systems operation. Since this issue is a complex and highly-constrained optimization problem, thus, the definition of appropriate objectivefunction to consider the protection constraints in the form of penalty function is one of the challenges of coordination problem. Until now, the objectivefunctions contains the sum of operation times of relays (main component) and the penalty function formed from the coordination constraints;however, it is suggested in this paper that the penalty function should be considered exponentially for increasing the pressure on it compared to the conventional one. Also, the new objectivefunction should be based on the multiplication operator. In this case, the main component is considered as the coefficient for the penalty function, and the pressure on the penalty function will increase because these two components have opposite behavior towards each other. It is concluded that, by using the proposed dynamic objective function in different conditions regarding different power networks, the new objectivefunction improves the performance of metaheuristic algorithms to penetrate to lower layers of search space and achieve better results than conventional static objectivefunctions.
Genetic algorithms (GA's) are mostly used as an offline optimisation method to discover a suitable solution to a complex problem prior to implementation. In this paper, we present a different application in which ...
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Genetic algorithms (GA's) are mostly used as an offline optimisation method to discover a suitable solution to a complex problem prior to implementation. In this paper, we present a different application in which a GA is used to progressively adapt the collective performance of an ad hoc collection of devices that are being integrated post-deployment. Adaptive behaviour in the context of this article refers to two dynamic aspects of the problem: (a) the availability of individual devices as well as the objectivefunctions for the performance of the entire population. We illustrate this concept in a video surveillance scenario in which already installed cameras are being retrofitted with networking capabilities to form a coherent closed-circuit television (CCTV) system. We show that this can be conceived as a multi-objective optimisation problem which can be solved at run-time, with the added benefit that solutions can be refined or modified in response to changing priorities or even unpredictable events such as faults. We present results of a detailed simulation study, the implications of which are being discussed from both a theoretical and practical viewpoint (trade-off between saving computational resources and surveillance coverage).
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