The optimal lifetime of the medium voltage underground cable networks of utilities

The effect of the lifetime of medium voltage underground cable networks on the network costs is studied. The cable manufacturer has estimated how much the cost of manufacturing the medium voltage XLPE power cable changes as a function of the cable lifetime. The shorter the lifetime, the cheaper the cable is, but a short lifetime leads to higher construction costs because the cable network must be rebuilt more frequently. The costs due to the cable network are represented by a simplified cost function, where the lifetime of the cable is a variable. The optimal lifetime of the medium voltage cable network is determined by minimizing the cost function over a long period of time. Besides the economic dimensioning of the underground cable network, the technical constraints and the effect of the lifetime of the cable network on the network configuration should be taken into account when minimizing the cost function. No real optimization method appears to exist for the problem. A network design program written at Tampere University of Technology (TUT) and a test network were therefore utilized in solving the problem