A Novel Finite-Element Optimization Algorithm with Applications to Power Cable Thermal Circuit Design

This paper presents the results of a recent study to develop an optimization model for underground power cable thermal circuit based on generated gradient approach. A new concept of perturbed finite-element analysis is utilized, which involves the use of derived sensitivity coefficients associated with various cable parameters of the interest. A subsequent utilization of such sensitivities as gradients of objective functions is realized in a general framework of power cable performance optimization. Therefore, based on the work of this paper, it is now possible to optimize the thermal circuit parameters including the thermal conductivities, boundary conditions and heat generation with respect to cable temperatures defined in a desired objective function and/or constraints. This enables more effective dealing with the nonlinearity of such temperatures, as implicit functions, using the more accurate perturbed finite element method. The proposed method minimizes the objective function value, without sacrificing the modeling accuracy in order to suit other exiting traditional methods. The developed algorithm was applied to various practical utility cable systems of 132-kV XLPE and 380-kV oil filled cables with their actual in-service configurations and for different practical cable performance optimization objectives demanded by the power utility operators.