Energieübertragung mit tiefgekühlten normalleitenden Kabeln : Optimierungsprobleme und Kostenstruktur

Heller, I.; Hofmann, A.

Book/Report

FZJ-2017-07433

Energieübertragung mit tiefgekühlten normalleitenden Kabeln : Optimierungsprobleme und Kostenstruktur

Heller, I.FZJ* ; Hofmann, A.FZJ*

1973
Kernforschungsanlage Jülich, Verlag Jülich

Jülich : Kernforschungsanlage Jülich, Verlag, Berichte der Kernforschungsanlage Jülich 954, 71 p. (1973)

Please use a persistent id in citations: http://hdl.handle.net/2128/15835

Report No.: Juel-0954-TP

Abstract: In this report the power transmission with normal-conducting low-temperature cables, especially the economic aspects, are worked out in detail. As useful cost-comparisons can only be done on optimised systems, studies on system-optimisation are most important. Calculations on the optimal temperature of the cryocable give the result, that there is a minimum of the costs of power loss (incl. investment-costs of the pefrigerators) around 25 K, but the complication of the conductors caused by the necessity of reducing skinand proximity-effect resul t in a displacement and nearly total elimination of the optimum. The costs of current-transportcannot be effectively lowered by deep cooling. The optimistic cost data of cryocables reported in the literature may be explained by the following arguments: - insulation of high-voltage can be done easier at low temperatures and allows a simpler design of the cable. - the power-limit of cryocables is much higher comparedwith conventional cables, thus the degression of specific cost typical for all types of cables can be utilizied. Some further criterions may be added which are not analysed concerning the costs in detail, for example low with of the cable trench related to the power rating, good overload capability, adaption to the growing load with low costs by extension of the cooling-stations (this argument applies especially to the liquid nitrogen ($LN_{2}$)-cable). As cooling with liquid hydrogen gives no substantial cost advantages, only the $LN_{2}$-cable is treated further on because this will be an easier and more reliable system. Two typical and especially promising concepts are investigated in detail - a single conductor tube-cable, which is electrically and thermally insulated by vacuurn - a three-conductor cable with litz-type conductors which is insulated electrically by wrapped paper impregnated with $LN_{2}$ and thermally by superinsulation under vacuum. The investment-costs and capitalized running costs related to the length and the transmitted power of the optimized systems are calculated at a nominal voltage of 110 kV and shown in dependence of power and length. Cable and cooling station can be devided in parallel independent units to increase the reliability of the system. The oncost of this provision is determined. By the following investigations on further details the results are refined and especially some unsafe points are examined more closely.As conclusion an economic comparison is done between the investigated types of a cryocable and an advanced normal-temperature-cable, that is an artificially cooled $SF_{6}$-cable. As this is done on a uniform basis, the result will surely have a high reliability. The comparison shows, that the $LN_{2}$-vacuum-tubecable is not competitive with the advanced $SF_{6}$-tube-cable within the whole region of power investigated. The $LN_{2}$-litz-conductor-cable on the other hand is able to cornpete when power and length are high. This is especially true, if it can be shown that the estimation of the frabrication costs of the conductor has been too pessimistic. Therefore experimental research on losses and fabrication problems of litz-conductors with high cross-sections are very important. The results of such investigations will be decisive on the good chances of a cryocable development.

Contributing Institute(s):