Five types of devices that can be connected at Device Connection Locations (DCLs) are now supported by the HIFREQ module (MultiFields, MultiFields+, MultiFields Pro, CDEGS software packages). These devices include switches, voltage sources, current sources, three-phase voltage sources, and database-driven devices. This feature allows users to simulate multiple scenarios with varying device states using a single HIFREQ model run, which is illustrated in this article through three real-world examples: an interference study involving a transmission line parallel to a pipeline, a train simulation assessing magnetic field exposure, and integrity testing of a grounding grid with a known defect.

This approach is based on the superposition principle in electromagnetics, which enables the combination of individual electromagnetic responses from distinct sources to determine the overall system behavior. DCLs act as virtual nodes within the HIFREQ network where external devices can be integrated. The initial solution computed by the solver is incomplete without specifying the behavior of these connected devices in a post-processing step. This approach offers significant computational advantages, allowing rapid exploration of device-dependent variations using a single HIFREQ run.

The ability to model metallic plates was introduced many years ago in the HIFREQ module of MultiFields. However, one limitation of the original model was its inability to account for magnetic flux generated by plates made of materials with high relative permeability.

SES has developed a new technique to address this limitation by accounting for the magnetic flux produced by currents within the plates. The validity of this technique was demonstrated in a UGC paper recently published.

This feature is integrated in the recently released Version 20 of HIFREQ. To activate this feature, set the Magnetic-Flux option in the Plate Settings under Define | Advanced Options, as shown below:

With this enhancement, plates in HIFREQ can now be used to accurately model scenarios including plates with high-permeability materials, such as various types of steel or Mu-Metal. This capability enables precise calculation of magnetic field shielding in open, closed, or perforated structures, helping to mitigate fields generated by low- and high-frequency sources including aboveground and underground power systems, transformers, trains, and more.

On a broader scale, the impact of transient phenomena, such as lightning strikes and HVDC faults, on equipment or systems enclosed within magnetic shielding structures can also be accurately modeled.

Now HIFREQ is capable of analyzing magnetic shielding effects even in the DC regime.

A new vertical multi-layer soil model in the HIFREQ module of the MultiFields software package is available in SES Software Version 20, enabling more realistic grounding and EMI analysis in environments with strong vertical resistivity transitions, such as riverbanks and canals. Unlike traditional models, this approach incorporates vertical soil boundaries, supporting full-wave solutions through the Unified Transform Method. The model supports flexible definition of conductor geometries and soil boundaries, and its accuracy has been verified through comparison with established analytical solutions and numerical simulations.

A detailed case study involving a 15-kA ground fault near a GIS substation crossing a low-resistivity river highlights the practical impact of vertical stratification. Results show significant deviations in leakage currents, fault current distribution, touch and step voltage levels when vertical boundaries are included, especially near the central tower and GIS. As shown in the following image, the vertical model predicts significantly higher touch voltages at the edge of the GIS grid closest to the river boundary, up to twice as high as the values computed using the multi-region model. While computation time approximately doubles compared to horizontal models, the approach remains efficient and more accurate than traditional FEM-based methods, making it a powerful tool for real-world grounding safety and EMI design in complex terrains.

The recent extension of the HIFREQ computation module in MultiFields to support finite volume analysis for arbitrary materials enables accurate modeling of complex electromagnetic environments involving conductors, plates, and heterogeneous volumetric regions. To evaluate the accuracy and practical applicability of this enhancement, three practical case studies were investigated. The first examined the impact of a submerged swimmer modeled as a set of resistive volumes on electric field and potential distributions near a faulted substation. The second analyzed the electromagnetic behavior of a shallow, salty swamp influenced by transferred potentials from a nearby substation grounding system during a fault. The third focused on induced currents in a transmission tower with a backfilled footing modeled as a finite volume, along with a nearby fence, under both steady-state and faulty conditions. These studies highlight the importance of finite volume modeling for capturing localized field interactions in complex or conductive environments. In each case, results obtained with HIFREQ were compared with those from the MALZ computation module in MultiGroundZ and showed close agreement.

In addition to these practical examples, the method was validated analytically using standard capacitor configurations. A multilayer dielectric system was modeled by placing finite-volume slabs with different permittivities between two metallic plates, in both series and parallel arrangements. The capacitance values computed by HIFREQ closely matched analytical solutions, confirming the numerical accuracy and stability of the approach. These results also demonstrated HIFREQ’s capability to model hybrid systems that combine metallic components with dielectric regions.

Together, the analytical validations and practical case studies establish the enhanced HIFREQ module as a reliable and versatile tool for electromagnetic analysis in environments involving horizontally layered soils, wires, plates, and heterogeneous volumetric regions.