Parameterized Macromodeling for Efficient Analysis of Wideband Tower Grounding Structures

Field solvers are often needed to properly characterize the behavior of grounding structures in a wide frequency range. These solvers provide accurate results but at high computational cost. Design tasks, such as design optimization and sensitivity analysis, require repeated simulations for different values of system parameters (e.g., conductor geometry and soil parameters). Parameterized macromodels are suitable to speed up design tasks without compromising the accuracy and reliability of the results. These models allow describing the system behavior as a function of frequency (or time) and system parameters. In this paper, we propose a parameterized macromodeling approach for grounding structures to characterize the system impedance behavior as a function of frequency and system parameters. The method initially calculates a set of frequency-domain root macromodels for a set of system parameters combinations. An adaptive frequency sampling approach is introduced for reducing the required number of frequency samples. The model behavior at any desired intermediate parameters values can then be calculated by an enhanced interpolation scheme that uses scaling coefficients obtained via optimization. Numerical results for a tower grounding electrode example validate the proposed approach and show that it can efficiently and accurately predict the multidimensional system behavior in frequency and time domain.