Hydropower stations, as critical infrastructure for basic energy supply, play a pivotal role in ensuring the reliability of power systems through their safe and stable operation. Grounding grids operating long-term in complex soil environments are prone to corrosion and degradation, disrupting current distribution balance and causing spatial asymmetry in the voltage field, thereby compromising system safety. Corrosion branch resistance increment identification based on the electrical network method is typically modeled as a parameter inversion optimization problem. However, this problem exhibits underdetermination and other characteristics, making it difficult for traditional analytical methods to obtain stable solutions. To address this, this paper proposes a quantum perturbation scheduling candidate pool-guided sine–cosine algorithm (QSPSCA). Building upon the classical sine–cosine algorithm framework, it incorporates a dynamic candidate pool with multi-source attractor points and a quantum-inspired long-tail scheduling local refinement operator. This achieves an enhanced and smooth transition between global exploration and local refinement. Comparative experiments based on the CEC2017 benchmark and a hydropower station grounding grid corrosion diagnosis case demonstrate that QSPSCA outperforms multiple comparison algorithms in terms of average optimality and result stability. Furthermore, QSPSCA is applied to three typical engineering-constrained optimization problems. Results demonstrate that, whilst satisfying engineering constraints, this method consistently yields higher-quality feasible solutions with superior convergence accuracy and stability compared to alternative algorithms. Therefore, QSPSCA is not only applicable to underdetermined inversion diagnostics but also provides a solution framework with broad applicability for complex engineering optimization problems under structural symmetry perturbations.

The electric substation grounding grid faces deterioration due to electrochemical reactions. The welding defects, acidic ambience, and inhomogeneity of conductor materials induce accelerated corrosion, and in severe cases, fractures may occur after a certain period of service time. However, periodic maintenance according to specifications cannot detect failure promptly, significantly increasing the risk to workers during electric substation operations. This study develops an intelligent life cycle maintenance framework through deep reinforcement learning and digital twins. Using practical inspection data and experimental results, reliable digital twins are established as the training environment for agents to determine the maintenance scheme. The intelligent agent dynamically optimises inspection intervals using historical resistance data and recognises corrosion trends, allowing for the replacement of steel sheets before failure happens. Monte Carlo simulations demonstrate that the agent can reduce personnel risk exposure by 25.7% while simultaneously saving 28.1% cost compared with the routine maintenance policy.

Workers involved with underground pipelines might be subjected to dangerous transient voltages caused by adjacent lightning strikes on electrical towers linked to grounding systems. To better understand and predict these indirect effects, this paper investigates the transient electromagnetic behavior of a tower– grounding grid–pipeline system subjected to a direct lightning strike. The entire setup is simulated using transmission-line theory to enable a thorough understanding and accurate modelling of wave propagation, electromagnetic coupling, and ionisation across the various system components. A large-scale setup comprising five transmission towers linked by a grounding grid, and located near an underground pipeline with a total length of 2.8 km, is considered in this paper. The lightning current of 12. 5 kA is delivered at the first tower's top, and the pipeline transient currents and voltages induced are calculated. The lightning-wave propagation from the strike location through the tower arms, grounding grid, and soil to the pipeline is investigated under the assumption of uniform soil conditions. Different soil resistivities (100, 300, and 600 m) are used to assess their effects on system behaviour. Three electrical pipeline models, all based on transmission-line equivalences, are constructed and compared. The first model explores only resistive effects, whereas the second and third gradually incorporate inductive, capacitive, and conductive elements, thereby enabling a more precise depiction of electromagnetic coupling and dielectric losses. According to the simulations, the lightning current amplitude fades progressively through the resistive, inductive, and capacitive components of the tower, grounding grid, and pipeline. As expected, the induced current is maximum at the struck tower, and it decreases along the system. About the first pipeline model, the induced voltages were always at a level safe enough for personnel, regardless of the soil resistivity considered. However, the second and third models showed a significant increase in pipeline voltage, with the third model exhibiting very high voltages despite lower current magnitudes. Hence, the results clearly underscore the importance of pipeline modelling, soil resistivity, and electromagnetic coupling in evaluating lightning-induced hazards. The modelling approach introduced here not only advances understanding of the transient behaviour of grounding systems and pipelines subjected to lightning but also enables the development of safer grounding layouts, pipeline materials, and protective measures that better shield people from lightning hazards.

This paper presents a numerical investigation studying the response of a new grounding system when submitted to different lightning current waveforms. This grounding system features an electrically conductive concrete (ECON) or geopolymer (ECG) square section with a standard steel rebar as an encased electrode (EE) at the center to potentially replace conventional copper or galvanized steel grounding grids in HV substations. Due to the specificity of this new grounding system called ECON/ECG-EE, we decided to perform different transient simulations using the RF module of the general FEM software Comsol Multiphysics 6.2 version. In the first step, both frequency (FD) and temporal domain (TD) analyses were validated using three grounding systems extracted from the literature. Next, several numerical new grounding system simulations were performed and compared with a conventional HV substation copper grid of the same dimensions equipped with vertical rods. We investigated the influence of several parameters, such as ECON/ECG and soil electrical conductivity, the rise-time in current lightning waveform and the frequency dependency of soil parameters. The numerical results obtained demonstrate that ECON/ECG-EE grounding systems submitted to lightning current pulse present a smaller peak impedance than conventional SGSs equipped with vertical rods, particularly in cases with high soil resistivity. Moreover, it was also demonstrated that with faster lightning current pulse, the ECON/ECG system’s peak impedance becomes significantly lower than those obtained for a copper grid with vertical rods.

Synergistic effects of Cl-/SO42- and sulfate-reducing bacteria on the grounding grid corrosion: performance, metabolites and mechanisms.

Pumped storage power stations commonly adopt impermeable linings at reservoir bottoms to reduce seepage losses. However, these linings significantly weaken the current dissipation capability of grounding grids, particularly in high-resistivity bedrock areas. To address this problem, a pipeline-type grounding grid (PTGG) with seepage holes is proposed for installation beneath impermeable reservoir basins. By enabling controlled water seepage, the PTGG increases bedrock moisture content and reduces its electrical resistivity, thereby improving grounding performance. A coupled seepage–resistivity–grounding model is established by integrating multiphase flow simulation in porous media with grounding impedance calculations using CDEGS. Simulation results indicate that controlled seepage can reduce the effective resistivity of initially dry bedrock from approximately 38,000 Ω·m to about 500–2000 Ω·m within the primary current-dissipation zone. For a typical pumped storage power station, the proposed PTGG reduces the overall grounding resistance by approximately 11.3–14.0% within 0.5–2 years of operation. Parametric analyses show that decreasing the spacing of seepage holes from 10 m to 1 m significantly enhances resistance reduction, whereas the influence of hole diameter (5–20 cm) on grounding resistance is relatively minor when the spacing is fixed. These results demonstrate that the PTGG provides an effective and site-specific resistance reduction solution for impermeable basin pumped storage power stations, where conventional grounding measures exhibit limited effectiveness.

Grounding systems play a very important role in ensuring the safety of individuals and equipment against electric shock hazards, and they contribute to the performance of equipment and protection systems during fault occurrences in high-voltage substations as well as in distribution systems. In the design of an electrical grounding system, the total ground resistance, the layout of ground rods, and their dimensions must first be determined. Moreover, the grounding system should be designed in accordance with international standards. The authors of this valuable study address the practical problem of designing a 220/110 kV substation grounding grid that is more secure and trustworthy. Employing CYMGRD software aligns with the IEEE 80 standard, considering important subterranean elements such as soil resistivity and seasonal moisture fluctuations. Future studies must, however, look at how it behaves in unforeseen circumstances, such as shifting faults and climate conditions, to completely guarantee its dependability. Ground potential rise is effectively set at 5734.72 V by a modeled grounding scheme with a grid resistance of 0.147 Ω, satisfying safety demands. Step and touch voltages are kept within safe bounds without needless complication by the design's careful coordination of mesh size and ground rod location. The simulation-validated suggested design provides a workable and practical solution for substation grounding. In this article, design solutions for single-phase-to-ground and double-phase-to-ground faults that may occur in a plant and can lead to problems such as increased ground potential and consequently dangerous touch and step voltages, are proposed in compliance with the IEEE 80 standard. These solutions aim to correct the grounding network and are structured in such a way that the layout of ground rods is optimized to keep touch and step voltages within permissible limits, thereby increasing the reliability of the grounding network.

The design of the AC substation grounding grid plays a pivotal role in maintaining safety during fault conditions. This paper presents a comparative study of grounding grid performance for various shapes of grounding grid, such as rectangular, square, triangular, L-shaped, and T-shaped. It mainly focuses on the number of conductors in X and Y directions, the number and length of ground rods, and the depth of installation of the grid. The outcome shows clear differences in grid behavior when the geometry and optimization parameters are changed. For each configuration, the ground resistance, ground potential rise, mesh voltage, and step voltage are assessed with respect to safety limits. The study presents that careful selection and optimization of the number of conductors in the X and Y directions, the number of ground rods, the length of ground rods, and depth can lead to obvious improvement in electrical safety as well as reductions in material usage and installation cost. Uniform soil resistivity is considered for the analysis of the grid using ESGSD software for obtaining an optimal design. This analysis provides useful direction for achieving safe and cost-efficient grounding grid layouts in practical substation applications.

This study investigates the corrosion behavior of laser powder bed fusion (produced in simulated soil environments with varying sulfate ion (SO 4 2− ) concentrations. As grounding grids critical components in power systems - face significant corrosion challenges in soil, this research evaluates the innovative application of 3D-printed 2205 DSS. The results demonstrated that increasing SO 4 2− concentration (0 to 1 mol/L) significantly enhanced the corrosion tendency of 2205 DSS, as evidenced by a negative shift in corrosion potential, increased corrosion current density, and reduced polarization resistance. SO 4 2− deteriorated the stability of the passive film, increased oxygen vacancy density, and promoted localized corrosion, thereby accelerating material degradation. Furthermore, the passive film formed in high SO 4 2− environments was thinner and more defective, further compromising corrosion resistance. The findings provide a critical knowledge gap in the field of additive-manufactured corrosion-resistant alloys for power infrastructure applications.

A new design of grounding grid based on multi-concentric rings with lower step and touch voltages compared to traditional grids

ABSTRACT Accurate characterization of subsurface electrical behavior during high‐energy fault events is critical for both geotechnical safety assessment and the protection of power infrastructure. This study presents a geophysically driven, time‐domain modeling framework for Ground Potential Rise (GPR) in multilayer and anisotropic soils, integrating electromagnetic field theory with physics‐informed arc resistance modeling. The methodology employs apparent resistivity profiling and soil impedance mapping, enabling high‐resolution simulation of current density and voltage gradients under realistic subsurface conditions. A coupled numerical–experimental approach is implemented: finite‐element simulations incorporating layered earth resistivity are calibrated against controlled fault injection tests using scaled grounding grids in stratified soil. The model achieves an average deviation of less than 4.7% from measured GPR and step/touch voltages, demonstrating strong predictive reliability. Results reveal that conventional steady‐state and homogeneous soil assumptions can underestimate hazardous step voltages by up to 63% and misrepresent the spatial extent of GPR zones by more than a factor of two. Comparative analyses show that optimized grounding grids reduce surface current densities by over 90% compared to isolated systems, significantly enhancing compliance with safety thresholds. Beyond its immediate application to substation and renewable energy grounding, the framework offers a transferable geoelectrical tool for infrastructure risk mapping, lightning hazard assessment, and geotechnical site evaluations in complex soil environments.

In this paper, the ground potential rise (GPR) phenomenon caused by lightning current injected into a field-shaped artificial grounding grid and the potential difference between different two nodes at the edge of the ground grid are observed and analyzed under the artificially triggered lightning. Based on circuit theory and measured current data, a π equivalent circuit is established to simulate the transient response of the grounding grid. The 19 return strokes (RSes) of three artificially triggered lightning were analyzed. The peak currents in the 19 return strokes range from −6.7 kA to −25.1 kA, and the mean value is −14.3 kA. The GPR decreased rapidly and formed a sub-peak after reaching the initial peak. Where the mean value of the initial peak is -148.65 kV and the mean value of the sub-peak is -92.87 kV. The GPR induced by the triggered lightning currents all showed sub-peak phenomena. The sub-peak phenomenon was found to be related to the localized corrosion of the vertical grounding electrode through simulation. Potential difference at the grounding grid edge represents a multi-pulse waveform with alternating polarity dominated by the positive pulse. The peak values of both positive and negative polarity pulses exhibit a gradual decrease, with the first positive pulse displaying significantly higher intensity compared to the subsequent pulses.

To address the challenges of on-site transient electromagnetic disturbance (TED) radiation testing for large-scale equipment under test (EUT), this paper presents an inflatable TED testing system based on a low-frequency-compensated transverse electromagnetic horn antenna. A theoretical model of an antenna with back-loaded matched impedance is proposed to enhance low-frequency radiation performance, and analytical expressions of the electric dipole moment and magnetic dipole moment are derived to establish design principles for the antenna. A wire-grid TED simulator (10 × 8 × 7 m3) is optimized through parametric studies on the arc transition structure, ground dielectric layers, grid layouts, and wire sagging effects. The testing system integrates an inflatable supporting structure and a 600 kV pulse generator, achieving a test volume of 4 × 4 × 4 m3 with a typical measured electric field with the rise time of 2.54 ns, the pulse width of 23.6 ns, and the peak field exceeding 50 kV/m. Notably, the collapsible inflatable design allows the entire system with outer dimensions of 11 × 12 × 9 m3 to be compacted into a transportable unit, enabling the on-site testing of large EUTs, such as high-voltage power transformers, without relocation.

Concealed conductive connections between a transmission tower’s grounding grid and its foundation can cause a portion of the lightning strike current to enter the foundation and concentrate at the concealed conduction locations, thereby increasing the risk of foundation deterioration. To investigate the impact characteristics of such currents on the foundation under this operating condition, this study first establishes an electro-thermal-mechanical coupled finite-element model of the tower foundation that incorporates a subsurface concealed conductive loop, and compares the foundation’s temperature rise and mechanical characteristics under lightning currents and under power-frequency follow currents. The results indicate that power-frequency follow current poses a substantially greater hazard to the foundation than lightning current. Based on similarity theory, scaling laws for the foundation subjected to the impacts of power-frequency follow current are then derived. Considering that the intrinsic electro-thermal properties of the foundation cannot be altered in the scaled model, a parameter correction method is proposed according to quasi-similarity criteria. The corrected scaled-model results are compared with those of the prototype in simulation, and principal indicators exhibit deviations within 3%. A physical scaled model was subsequently designed and fabricated for impact testing, and ultrasonic inspection was used to assess potential damage in the concealed conduction region. The results show that under the action of power-frequency follow currents, the maximum temperature at the concealed conductive region reaches 124 °C, with deviations of 2.83% from the prototype simulation and 3.58% from the scaled-model simulation. The tower foundation was subjected to 20 power-frequency follow current impacts. After each impact and subsequent cooling, ultrasonic measurements of wave propagation velocity at the concealed conduction center decreased from 3.797 km/s to 3.571 km/s. The observed reduction in wave speed indicates a loss of local concrete structural integrity and suggests the risk of performance degradation and initiation of microcracks. These findings provide a reference basis for assessing the safety of tower foundations under concealed conduction conditions.

With the rising demand for electricity and the expansion of power generation facilities, grounding systems have become critical for ensuring human safety and equipment protection. This study employs the finite element method to model single- and double-layer grounding networks, evaluating their effectiveness in mitigating step and touch voltages. Findings reveal that, despite increased complexity and cost, the double-layer configuration does not significantly enhance ground resistance reduction or voltage distribution, indicating that the single-layer network remains a reliable and efficient solution.

As the primary discharge channel for fault currents, substation grounding grids are crucial for ensuring the safe and stable operation of power systems. Due to its non-destructive and efficient nature, the pulsed eddy current (PEC) method has become a research hotspot in grounding grid detection in recent years. However, during the detection process, the signal is severely interfered with by substation noise, seriously affecting data quality and interpretation accuracy. To address the problem of suppressing both power frequency and random noise, this paper proposes a composite denoising method that combines bipolar cancellation, minimum noise fraction (MNF), and mask-guided self-supervised denoising. First, based on the periodic characteristics of power frequency noise, a bipolar pulse excitation and differential averaging process is designed to effectively filter out power frequency interference. Subsequently, an MNF algorithm is introduced to identify and reconstruct random noise, improving signal purity. Furthermore, a mask-guided self-supervised denoising model is constructed, using a segmentation convolutional neural network to extract signal-noise masks from noisy data, achieving refined suppression of residual noise. Comparative experiments with simulation and actual substation noise data show that the proposed method outperforms existing typical noise reduction algorithms in terms of signal-to-noise ratio improvement and waveform fidelity, significantly improving the availability and interpretation reliability of pulsed eddy current data.

Abstract. Grid-wise Vienna Mapping Functions 1 (VMF1) and Vienna Mapping Functions 3 (VMF3) tropospheric products are widely used to interpolate the a priori zenith hydrostatic delay (ZHD) and zenith wet delay (ZWD) over GNSS (Global Navigation Satellite Systems) stations for the mitigation of tropospheric delays contained in GNSS observations. Since these two products provide ZHD and ZWD values only for the ground surface at global grid points, the ZHD and ZWD at the four grid points nearest to a GNSS site used to interpolate for the GNSS site need to be reduced to the same height of the GNSS station before a horizontal interpolation (e.g., bilinear interpolation) is implemented. However, the accuracy of the officially recommended reduction model may not be as good as desired, especially in the case that the height of the GNSS site largely differs from that of the four ground grid points. To address this, a new vertical reduction model for reducing the ZHD and ZWD at the height of grid points to a target height was developed. The sample data for the modelling were the 10-year (2010–2019) ZHD and ZWD profiles over grid points obtained from ERA5 monthly averaged reanalysis data, while the 3-year (2020–2022) radiosonde profiles and the IGS (International GNSS Service) site-wise zenith tropospheric delay (ZTD) products were used to evaluate the new model. Results demonstrated that the accuracy of ZHD, ZWD, and consequently ZTD values interpolated from VMF1/VMF3 products and the new model considerably improved compared to traditional methods, especially at the target sites that have large height differences from its closest VMF grid points. This improvement has significance for those applications that need to use tropospheric delay corrections, e.g. in GNSS positioning and GNSS meteorology for a desired accuracy.

Introduction: Grounding grids are crucial for power system safety, but corrosion can lead to failures. Traditional corrosion diagnosis methods have limited accuracy due to environmental interference, particularly in multi-branch corrosion detection. This article proposes an improved algorithm that combines minimum error, Tikhonov regularization, and iterative techniques to enhance fault detection. Methods: The proposed method divides the grounding grid into "internal" and "external" networks, allowing for the accurate modeling of fault conditions. A diagnostic equation is formulated that relates the change in port resistance to the branch fault, and the least-squares Tikhonov algorithm is applied to refine the solution. This reduces the ill-conditioned nature of the equation, thereby improving accuracy. The algorithm is verified for its feasibility through Multisim simulations and further tested in MATLAB to evaluate its robustness under different fault conditions. Results: Simulation results confirm that the proposed algorithm significantly outperforms traditional methods in diagnosing multi-branch corrosion. The least squares Tikhonov regularization effectively alleviates the ill-conditioned problem and obtains a solution closest to the preset fault value with the minimum error. Multisim simulation proves the success of fault location. And MATLAB verification confirms the reliability of this method under different grid conditions. The algorithm achieves higher accuracy in fault detection, particularly in complex multi-branch scenarios. It should have practical applicability for a large-scale grounding grid. Discussions: The proposed grounding grid fault diagnosis algorithm integrates the minimum error method, Tikhonov regularization, and iterative techniques to achieve optimal results. Compared to the traditional method, it offers significant improvements in accuracy, robustness, and applicability to multi-branch corrosion scenarios. The least-squares Tikhonov regularization effectively addresses the ill-conditioned nature of the fault diagnosis equation, alleviating the instability of the solution caused by measurement noise and environmental interference. Conclusion: The proposed method enhances the accuracy of grounding grid fault diagnosis, particularly in complex scenarios involving corrosion. It provides a practical solution for grounding grid maintenance of the power system. Future work can focus on product development and field application.

Accurate estimation of a suitable soil model and its parameters from field resistivity measurements, as well as the apparent soil resistivity based on this model,is vital for the reliable design of grounding systems in substations with high voltage. In this study, the two-layer soil model parameters are estimated based onThe Institute of Electrical and Electronics Engineers (IEEE) Standards using Kronecker-sequenced genetic algorithms (GAs), with lower error values compared tothose in the literature. The estimated parameters are upper and lower layer soil resistivities and upper layer depth. Furthermore, grounding grids are individually designed for both uniform and two-layer soil models using Kronecker-sequenced GAs. The design parameters are the number of rods, meshes, and gridburial depth. In the grounding grid designs, in addition to safety requirements, cost minimization is a key objective. Subsequently, the uniform soil model designparameters have been applied to the two-layer soil model, and the two-layer soil model design parameters to the uniform soil model. This approach enabledthe assessment of whether the grounding grid design parameters obtained for one soil model type (uniform or two-layer soil models) could satisfy safety criteria when applied to the other. Thus, conclusions are drawn on the suitability and reliability of uniform and two-layer soil models for grounding system design. Inthis study, without using very expensive commercial software, Kronecker-sequenced GAs are employed for the estimation of two-layer soil model parametersand the apparent soil resistivity corresponding to the uniform soil model, the grounding grid design, and the evaluation of soil model suitability.Cite this article as: B. Gürsu, “Determination of appropriate soil model and parameters for grounding system of substation with high voltage via Kroneckersequenced genetic algorithms,” Turk J Electr Power Energy Syst., Published online September 11, 2025. doi: 10.5152/tepes.2025.25026.

The grounding grid is an important component of the substation, and its corrosion will directly influence the safe operation of the power system. In order to overcome the limitations of traditional corrosion diagnosis methods, the corresponding corrosion diagnosis equations model was constructed by using electric network theory. Considering the limited number of measurable nodes in the actual substation, which leads to the characteristics of high-dimensional underdetermination of the equations, an improved RMSProp-Lookahead hybrid optimization algorithm was proposed to solve the problem. The method combined the Gradient normalization mechanism and the Lookahead dual update strategy, optimized the hyperparameter configuration through grid search, and improved the convergence speed and global search capability of the optimization process. The simulation and experimental results showed that the method can effectively locate the corrosion branch, accurately judge the corrosion degree, and significantly improved the diagnostic efficiency and accuracy, which has important practical significance for the safety maintenance of the grounding network.