Life cycle cost analysis of transmission and distribution systems

Abstract

For state-of-the-art electrical devices efficient and reliable operation is of particular importance. They must execute their function safely, if possible lifelong, and must be as economical as possible over their complete lifetime. Concerning the assessment of single units like circuit breakers, transformers, overhead lines etc. the life-cycle-cost method has been used for quite a long time. The concept of Life-Cycle-Cost means to take into account not only the manufacturing cost, but also to consider the operational and disposal costs. In this case the method supports the cost assessment of equipment, while enabling a comparison of different equipment features. In principle, this approach related to single devices can also be transferred to a complete system consisting of overhead lines and substations. The calculation of Life- Cycle-Costs in this work is performed in accordance to IEC 60300-3-3 "Dependability management Part 3-3: Application guide - Life cycle costing ". In this paper, a Life-Cycle-Cost analysis is performed covering a complete 110 kV overhead transmission grid with air insulated substations. The results depict the main cost-driving or most important elements of the system. On this basis, different maintenance strategies have been applied and investigated into. Moreover, the Life-Cycle- Cost method can be used effectively for comparing different network topologies and equipment types. In this case the method can quickly locate the cost-driving elements. Finally, these elements are particularly taken into account by a weighted risk analysis. (4 pages)