A novel approach based on reliability sensitivity analysis to allocate protective devices

Authors: HAMED HASHEMI DEZAKI, HOSSEIN ASKARIAN ABYANEH, MEHDI GARMRUDI, HOSSEIN MAHDINIA, KAZEM MAZLUMI

Abstract: In electrical distribution systems, it is possible to have a reliable system via a well-designed protective scheme. The allocation of protective devices is an important parameter in the design of a protective scheme. Different approaches to optimize the allocation of protective devices have been studied. Because of some uncertainties, it is not the best strategy to select an optimized solution in accordance with certain conditions. The availability of the protective devices seriously affects the reliability of electrical distribution systems. Furthermore, reduction of the investment in some designing processes leads to a decrease in the number of protective devices that will be installed. By considering the insensitivity of malfunctioning or removed protective devices, it is possible to select a flexible scheme having a minimal reliability decrement due to the malfunction or removal of protective devices. Sensitivity analysis is an appropriate way to determine system robustness against the uncertainties of the model or design parameters. In this article, the reliability sensitivity level is examined according to the allocation of the protective devices. The system average interruption index (SAIFI) variation is selected as the reliability level. In the proposed method, the SAIFI variation is calculated when a protective device malfunctions or is removed. A higher sensitivity level signifies a device having a more proper allocation. Moreover, to prevent any malfunctions, that device must be preserved and revised continuously. Hence, the proposed method can be used to improve the system reliability by adding the protective device to the most appropriate location. To illustrate the efficiency of the introduced method, it is applied to a typical distribution network.

Keywords: Sensitivity analysis, malfunction and removal of protective devices, system reliability, protection devices, system average interruption frequency index

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