Study On Technical And Economical Evaluation Method Of Cable Line Steel Support Based On Life Cycle Cost

With the rapid development of the national economy,the power consumption of the society has increased rapidly,and the voltage level of the cable is also getting higher and higher.Under the action of large current of power cable,the steel support has electromagnetic induction in alternating magnetic field,resulting in large eddy current loss.Eddy current loss increases the extra line loss of power system,which leads to the waste of electric energy.The heat generated by eddy current loss of cable steel support is not easy to dissipate,which makes the temperature of the support itself rise.Metal steel support will suffer from thermal fatigue failure for a long time under repeated thermal stress.Thermal fatigue failure affects the service life of steel support,resulting in additional economic losses to the power system.Therefore,it is necessary to determine the scientific and reasonable evaluation method of the cable steel support,guide the planning of the cable steel support to reduce the unnecessary economic losses and maximize the economic and social benefits.In this paper,the loss cost of the cable line steel support due to the waste of the electric energy caused by the eddy current loss and the thermal fatigue failure caused by the temperature rise of the cable line steel support during the operation of the cable line are considered to put forward a techno economic evaluation method of steel support for cable line based on life cycle cost.The life cycle analysis of steel support for cable line is carried out,and the life cycle cost model of steel support for cable line is established.The loss cost caused by eddy current loss is taken into account in the life cycle cost of cable lines,and the thermal fatigue life of the cable line steel support is used as the service life of the cable support to analyze the economical type of square steel support,angle steel support and channel steel support and carry out the optimal design and type selection.Based on the economic evaluation of the steel support of the cable line with life cycle cost,this paper set up the life cycle cost model of the cable line steel support,which detail the initial investment cost,operation cost,maintenance cost,deformation failure and waste cost of the cable line steel support from the planning to the scrap.The initial investment cost,operation cost,maintenance cost,deformation failure cost and waste cost can be determined through the investigation of cable lines,and the operating cost is the loss cost caused by the eddy current loss during the operation of cable line steel support.We build the three-dimensional finite element model of three kinds of steel support of channel steel,square steel and angle steel respectively.The electromagnetic and thermal properties of the cable support are analyzed based on the electromagnetic fluid temperature multi physical coupling field.We obtain the eddy current loss power of three kinds of cable steel supports in the calculation of electromagnetic field,and calculate the eddy current loss cost of the steel support of the cable line.Because there is no forced convection in the cable line,the fluid field model is set as natural convection.The joule heat calculated by electromagnetic field is loaded into the flow field temperature field through indirect coupling method to get the temperature rise of three kinds of steel supports.In order to verify the correctness of the calculation method of the electromagnetic-fluid-thermal field of the cable support,we set up the cable support temperature rise platform.The error between the experimental data and the simulation data of the cable support temperature rise platform is 3.5%,less than5%.It is considered that the electromagnetic-fluid-thermal field simulation method is correct,so the correctness of the temperature rise calculation of cable support is verified.The support temperature of cable support increases due to its eddy current loss,and thermal fatigue failure occurs when alternating heat load is applied.We take the temperature of three steel supports obtained from fluid temperature field into the structure field as load to analyze the thermal stress of cable support.Combined with the S-N curve of steel material,the thermal fatigue analysis of three steel supports is carried out to calculate the service life of the steel support of the cable line.Based on the life cycle cost,we carry out the economic evaluation of the steel support of Feng Luo cable line,and calculate the life cycle cost of the three steel supports.The least life cycle cost is the best one.This paper presents a new economic evaluation method for cable support,which takes full account of the cost required during the whole service life of the cable support and evaluates the cable support from two aspects of technical and economic performance.It has important reference significance for improving economic benefit and reliable operation of power system.The innovation and characteristics of this article are as follows:(1)We propose a technical and economical evaluation method of cable line steel support based on life cycle cost,and set up the life cycle cost model of cable line steel support to study the cost of cable line steel support from design to decommissioning.It provides scientific and reasonable guidance for the planning of steel support of cable line.(2)Considering the loss cost caused by the eddy current loss during the operation of the cable line steel support,the cost of the loss of the eddy current loss is included in the operating cost of the life cycle cost model of the cable line steel support.The thermal fatigue life of the steel support of the cable line is calculated,and the thermal fatigue life of the steel support is taken as the life cycle of the steel support of the cable line.More scientific support for the planning of steel support for cable line.