The Reliability of Power Distribution Systems as Calculated Using System Theoretic Concepts

Reliability of distribution systems is an importantissue in power engineering for both utilities and customers. Power distribution reliability is closely related to individual component reliability. In this paper, the reliability as measured by certain count indices, mainly the System Average Interruption Duration Index (SAIDI) and the System Average Interruption Frequency Index (SAIFI), is quantified in terms of individual distribution component reliability. This is an extension of previously reported results. The value of the approach lies in distribution expansion planning in which a radial system may be networked with a view to improve reliability. The effect of inserting Distributed Generation (DG) in the distribution system is studied in this paper. The result of this insertion may be that the number of outages increases because of the possible failure of the DG hardware. Two new indices for this application are proposed: the ratio of DG energy to interrupted energy and the ratio of DG operating duration to outage duration.The paper proposes a dynamic model of distributed generation in the smart grid, based onenvironmental compensation costs, traditional DG capacity cost, DG operation and maintenance costs, purchased power cost and network loss cost. The model can reflect the DG environment-friendly features. In this paper, the HS (Harmony Search) algorithm is used for optimum placement and sizing of DGs in order to decrease the losses and increase the reliability in a standard grid. The proposed method for sizing and sitting of the DG capacities in the grid is so proper and useful in comparison with the conventional method.

Keywords:

Distribution Systems , Reliability , Optimum location