Power system reliability and its assessment. III. Distribution systems and economic considerations

For pt.II see ibid., vol.6, no.6, p.291-7 (1992). A power system containing generation, transmission and distribution can be divided into the three hierarchical levels. The author discusses the third level, or more specifically to the distribution facilities and the general considerations of reliability cost and reliability worth. Consideration of the third hierarchical level would enable the effect of generation, transmission and distribution on individual customers to be evaluated and compared against relevant design and operational criteria. Although this total effect can be monitored realistically in terms of past performance measures, it is usually impractical for future system predictions because of the size of the problem. Instead the predictive assessment is usually done for the distribution functional zone only. This is acceptable because: distribution networks generally interface with the transmission system through one supply point; and distribution systems are generally the major cause for the outages seen by individual customers and therefore dominate the overall reliability indices