Optimization of Power Cable and Thermal Backfill Configurations

The design problem of selecting the optimal parameter values associated with cable trench and thermal backfill is formulated as a nonlinear programming problem and solved using a multi-dimensional gradient optimization method. The technique considers all design parameters simultaneously and provides the optimal solution which either minimizes the cost of backfill and trench production subject to an ampacity constraint or maximizes the cable ampacity subject to a cost constraint. In either formulation, upper and lower bounds on design parameters as well as other thermal and physical constraints are included. The important role of backfill parameters in reducing the effects of environmental fluctuations on cable ampacity is exploited in the optimization analysis via defining functional sensitivity profiles which may be used to ensure secure and reliable designs. The paper includes a description of the computer program which was developed for the optimization of general cable configurations in thermal backfill.