Analysis And Management Of Life-cycle Cost Of Underground Substation Based On Fuzzy Theory

With the continuous expansion of city scale and the increase ofelectricity load, it has become a trend to build underground substationswith high voltage level (110kV,220kV or500kV) in urban area. In orderto improve the land and capital utilization of underground substation, andto better guide its planning, construction and operation management, theconcept and method of life-cycle asset management (LCAM) have beenapplied more and more. The main goal of LCAM is to minimize thelife-cycle cost (LCC), meanwhile ensure the safety and reliablity of thesubstation·s operation. The core issue about LCAM is to estimate theLCC beforehand, as well as to generate the strategy of management andmaintenance after the substation has been put into operation.The traditional cost accounting for engineering projects often facesproblems such as lack of data and impact of uncertainty factors, whichwill reduce the effectiveness of the accounting a lot. In view of this, thispaper introduces fuzzy theory into the analysis and management ofunderground substation·s LCC.First, all the costs happened during the life-cycle of underground substation, from the investment and construction, to operation andmaintenance until scrap recycling, are analysed in details. And on thebasis of the analysis, a basic estimation model of undergroundsubstation·s LCC is built.Then, a fuzzy estimation model for underground substation·s LCCbased on the fuzzy smooth theory is put forwand. According to relevantdata of typical local underground substations at work, the fuzzy smoothmethod is used to forecast some LCC components of a new undergroundsubstation, then, the forecasting results are fuzzified and fuzzy functionoperations are used to get the final LCC fuzzy estimation result.At last, through the research of the maintenance strategy for electricalequipments, the importance and feasibility of underground substation·sLCC management are discussed. First, use the method of fuzzy timeseries to forecast the equipment·s reliability parameters, and thenaccording to fuzzy programming theory, a maintenance strategyoptimization model based on LCC for electrical equipments is established,which will certainly be beneficial for the operarion and maintenancemanagement of underground substation.The application examples of underground substations in a southerncity show the effectiveness of the models proposed in this paper. Thefuzzy estimation results can be more scientific and reasonable;meanwhile, the maintenance strategy can effectively achieve the goal of LCC minimization and ensure the balance between utility and cost. All ofthese achievements will provide a beneficial reference for the planning,construction and operation management of underground substation in citypower grid.