Reliability evaluation of underground distribution networks using representative networks

There has been a shift in focus in the regulation of distribution network monopolies, from asset based to performance-based regulation. The overall distribution revenue is a function not only of the operating and capital costs incurred by the network owner in providing the service, but also depends on the quality of customer service. Moreover, present regulation continues to encourage year-on-year performance improvements and requires that these improvements be achieved in a cost-effective way. Clearly, there is a need for a framework that enables network performances to be objectively compared, the differences to be understood and explained, and cost and benefits of alternative distribution network investment strategies to be evaluated (improvements in customers' service). The essential idea has been to analyse a small number of networks that represent large number of real feeders of the system. The approach can be used to assess individual companies on an absolute basis or to compare the relative performance between companies. Furthermore, representative networks could be optimised to achieve a most favourable balance between network expenditure and benefits in the form of improved performance. This process consists on the calculation of reference networks which would then enable the design of efficient investment policies.