A multistage concept for distribution system planning

The electric distribution system is exposed to continuous expansion due to occurrence of new load points or increase of the load in the existing points. The expansion in distribution system can be done when the existing demand is increased and/or new demand comes by small incremental steps. But sometimes unplanned expansion may increase the overall cost over a life cycle. Life cycle cost analysis for distribution system planning ensures the minimum expansion cost along with line power loss over the life of the system. Life cycle cost is defined as the total cost which includes purchase cost, fixed cost, depreciation cost, inflation, maintenance cost and all other costs caused at every stage over multistage planning periods. In this work, the life cycle cost has been evaluated for different planning strategies and results are compared. A number of case studies have been presented to show the importance of the analysis.