This study investigates the corrosion behaviour of grounding down leads in transmission towers subjected to wet-dry cycle in saline soils of Northwest China through accelerated corrosion experiments. Using saline soil from the Hexi Corridor, rich in chloride and sulphate ions, corrosion rates were assessed via weight loss, polarisation curves, scanning electron microscopy and X-ray diffraction analyses. Results demonstrate that wet-dry cycle significantly accelerates corrosion due to enhanced chloride ion diffusion and corrosion kinetics, with the highest average weight loss rate (3.08%) and corrosion current density (0.3526 mA/cm(2)). Scanning electron microscopy analysis revealed extensive cracking in corrosion product layers under cyclic wet-dry conditions, weakening their protective capability and further intensifying corrosion. The primary corrosion products identified were FeO and Fe2O3, consistent with field samples, indicating that the corrosion mechanism remains unchanged under accelerated conditions. This study provides novel insights into how cyclic moisture conditions affect grounding materials in saline environments, guiding material selection, maintenance strategies and site selection to improve transmission line reliability and safety.

This paper presents a comprehensive assessment of the accuracy of high-frequency (HF) earth meters in measuring the tower-footing ground resistance of transmission line structures, combining simulation and experimental results. The findings demonstrate that HF earth meters reliably estimate the harmonic grounding impedance (R25kHz) at their operating frequency, typically 25 kHz, for a wide range of soil resistivities and typical span lengths. For the analyzed tower geometries, the simulations indicate that accurate measurements are obtained for adjacent span lengths of approximately 300 m and 400 m, corresponding to configurations with one and two shield wires, respectively. Acceptable errors below 10% are observed for span lengths exceeding 200 m and 300 m under the same conditions. While the measured R25kHz does not directly represent the resistance at the industrial frequency, it provides a meaningful measure of the grounding system's impedance, enabling condition monitoring and the evaluation of seasonal or event-related impacts, such as damage after outages. Furthermore, the industrial frequency resistance can be estimated through an inversion process using an electromagnetic model and knowing the geometry of the grounding electrodes. Overall, the results suggest that HF earth meters, when correctly applied with the fall-of-potential method, offer a reliable means to assess the grounding response of high-voltage transmission line structures in most practical scenarios.

When a long distance HVDC transmission system discharges current into the earth through its grounding electrode, ground potential differences appear in a large area. And therefore part of the DC current may flow into nearby pipelines which may be dangerous to the equipment and personnel, and may aggravate corrosion. In this paper, an equivalent circuit based on the method of moments is introduced to calculate the current and potential distributions along a pipeline with damaged anticorrosive coating. The current-dependent electrochemical polarization potential between soil and the metal pipe, due to the damage of the anticorrosive coating, is taken into account by using the Newton-Raphson scheme. The circuit is verified through a reduced scale experiment. By examining the circuit, the effect of the damaged anticorrosive coating on the leakage current and the pipe potential with respect to soil along the pipeline is analyzed.

This paper proposes an Artificial Neural Network (ANN) model using a Multi-Stage method to optimize the configuration of an External Lightning Protection System (ELPS) and grounding system. ELPS is a system designed to protect an area from damage caused by lightning strikes. Meanwhile, the grounding system functions to direct excess electric current from lightning strikes into the ground. This study identifies the optimal protection system configuration, reducing the need for excessive components. The ELPS configuration includes the number of protection pole units and the height of the protection poles. In contrast, the grounding system configuration consists of the number of electrode units and the length of the electrodes. This study focuses on the protection system configuration at a Photovoltaic Power Station, where the area is highly vulnerable to lightning strikes. Several aspects need to be considered in determining the appropriate configuration, such as average thunderstorm days per year, ELPS efficiency, total area of photovoltaic module, area to be protected, soil resistivity, electrode spacing factor, and the total required electrode resistance. The proposed multi-stage ANN model consists of three processing stages, each responsible for handling a portion of the overall system tasks. The first stage is responsible for determining the protection pole configuration. In the second stage, the Lightning Protection Level (LPL) classification is performed. Then, in the third stage, the process of determining the grounding configuration is handled. The analysis results show that the Multi-Stage ANN model can effectively determine the configuration with a low error rate: MAE of 0.265, RMSE of 0.314, and MPE of 9.533%. This model can also explain data variation well, as indicated by the high R2 value of 0.961. The comparison results conducted with ATP/EMTP software show that the configuration produced by ANN results in fewer protection pole units but with greater height. Meanwhile, ANN produces a configuration with shorter electrode lengths but fewer units in the grounding system.

Two types of grounding systems are recommended for use in the international standard IEC 62305-3, Part 3: Physical damage to structures and life hazard. One of these is a radial-based grounding system (type-A), which is used in soil resistivities of up to 3000 Omega m and is considered in this paper. It is a well-known fact that during lightning strikes, only a part of the grounding wire contributes to dissipating the lightning current into the surrounding soil. This effective part of the grounding system depends on several features, such as soil resistivity, burial depth, and rise time of the dissipated lightning current. The effect of all of these features on the effective length of the type-A grounding system is explored in this paper. A suitable supervised machine learning regression model is developed, which will enable readers to accurately approximate the effective length of the type-A grounding system for realistic values of input features. The trained model in the paper yielded an R2 value of 0.99998 on the test set. In addition, two simple mathematical formulas are also provided, which produce similar but less accurate results (R2 values of 0.989883 and 0.998557, respectively).

The electrical network, essential to our society, frequently encounters disruptions from lightning strikes, resulting in material damage and power blackouts. Swift diversion of lightning currents to the ground is imperative to safeguard the grid. This study proposes a proportionality coefficient (K) to effectively distribute lightning current between grounding and network flow. The optimality of this coefficient depends on the tower grounding system resistances; lower resistances facilitate optimal distribution, enabling more current to flow to the ground. In the examination of the Djiri-Ngo power line in the Republic of Congo, grounding systems were optimised based on soil types. Three electrodes were used for clayey sand, while fifteen were employed for siliceous sand. Optimal coefficients were determined to be 0.86 for clayey sand and 0.81 for siliceous sand. These coefficients denote that 86% and 81% of the lightning current were directed to the ground, in contrast to non -optimal resistances (69% and 29% with a single grounding electrode). The experiments highlight the importance of adapting grounding systems to soil characteristics, rather than adhering to a uniform approach. Efficient diversion of lightning current to the ground is paramount for grid protection.

Lightning strikes can cause equipment damage and power outages, so the distribution system's reliability in withstanding lightning strikes is crucial. This research paper presents a model that aims to optimise the configuration of a lightning protection system (LPS) in the power distribution system and minimise the System Average Interruption Frequency Index (SAIFI), a measure of reliability, and the associated cost investment. The proposed lightning electromagnetic transient model considers LPS factors such as feeder shielding, grounding design, and soil types, which affect critical current, flashover rates, SAIFI, and cost. A metaheuristic algorithm, PSOGSA, is used to obtain the optimal solution. The paper's main contribution is exploring grounding schemes and soil resistivity's impact on SAIFI. Using 4 grounding rods arranged in a straight line under the soil with 10 Omega m resistivity reduces grounding resistance and decreases SAIFI from 3.783 int./yr (no LPS) to 0.146 int./yr. Unshielded LPS has no significant effect on critical current for soil resistivity. Four test cases with different cost investments are considered, and numerical simulations are conducted. Shielded LPSs are more sensitive to grounding topologies and soil resistivities, wherein higher investment, with 10 Omega m soil resistivity, SAIFI decreases the most by 73.34%. In contrast, SAIFIs for 1 klm and 10 klm soil resistivities show minor decreases compared to SAIFIs with no LPS. The study emphasises the importance of considering soil resistivity and investment cost when selecting the optimal LPS configuration for distribution systems, as well as the significance of LPS selection in reducing interruptions to customers.

The aim of this work is to analyze the effectiveness of Bentonite, Kenaf and Pine Wood mixtures as enhancement materials for grounding system purposes. Grounding systems are designed to dissipate high-magnitude fault currents to Earth and provide safety to persons working in or living near power system installations. They are also necessary to protect equipment from being damaged caused by lightning strikes. The safety and reliable operation of various applications in an electrical system is highly depending on the effectiveness of the grounding system installed which could be achieved with a low resistance path, and this can be obtained by employing grounding enhancement materials to the surrounding soil of the installation site. Hence, this is highlighted in this work where NEM mixtures grounding systems were installed at a site near to SGS, UPM with a high resistivity soil profile. Kenaf is a natural fiber that has been shown to be effective in improving the performance of grounding systems as it has a high conductivity and a high dielectric constant. This means that it can carry electrical current well and it can also store electrical energy. Kenaf is also a relatively inexpensive material, which makes it a cost-effective option. The unique properties of Bentonite, a clay material, and Pine wood, a natural insulator, make them promising options for improving grounding systems. Six grounding systems were installed with 100% Bentonite, 100% Pine, Bentonite and Pine Mix, Bentonite and Kenaf Mix, Pine and Kenaf Mix, and Reference grounding systems. A comparison was made between them using daily measured earth resistance from 2nd March 2023 until 10th July 2023, i.e. for 130 days. It was found that mixtures of Bentonite and Pine Wood performed better than the 100% Bentonite.

Grounding systems play a crucial role in protecting an electrical power system in order to provide a safe path for fault current flow dispersion, especially in the event of lightning to avoid damage towards electrical equipment and malfunctions of such system. Therefore, an effective grounding system should possess low current resistance, allowing the fault currents to flow in the least resistance path as quick as possible. There are several methods to obtain an effective grounding system with low earth resistance value. The most common is by introducing enhancement materials, which either natural or chemical based. Note that only Natural Enhancement Materials were employed in this work which include Bentonite, Gypsum, Vermicast, Coco Peat and Peat Moss, which were chosen based on their moisture retaining capabilities. This is due to the reason that Natural Enhancement Materials will not alter the characteristics of the surrounding soil and proved to be environment friendly, as opposed to the Chemical Enhancement Materials. A total of 15 samples with various ratios including 4 Soil Reference samples, i.e. from previous Grounding Systems 2016/2017, 2017/2018, 2018/2019 and 2019/2020, were tested. Moisture Retaining Test were conducted twice a week starting from 11th March 2022 until 10th May 2022, for a duration of 60 days once Volume Density Test was performed towards the 100% individually mixtures on day-0. It was concluded that the four best performed NEM mixtures in descending order were found to be Bentonite and Gypsum Mix A (86.72%), 100% Bentonite (86.59%), Bentonite and Coco Peat Mix A (79.69%), and Bentonite and Peat Moss Mix A (79.51%). Note that Bentonite ratio was more in Mix A compared to Mix B.

Grounding systems is a fundamental part in an electrical power engineering system. It is important for ensuring the safety of occupants, to protect electrical equipment from damage, minimize the risk of electrical hazards and maintain a stable system during both normal and fault conditions. Hence, a grounding system must provide a path for fault currents to safely dissipate into Earth while preventing electrical shock hazard, and reduce and limit the damage to any electrical equipment connected to it. However, traditional grounding systems may not always be able to provide the required level of conductivity, especially in high soil resistivity sites or in applications where high fault currents are anticipated. Resistivity of the surrounding soil is one of the parameters that can be easily manipulated for an efficient grounding system to be made available as it is influenced by factors such as geographical location, moisture content, temperature, and soil composition. In regions with poor natural soil conductivity or environments characterized by seasonal fluctuations in resistivity, the deployment of natural enhancement material is merged as a critical solution. In this work, three sites located around Universiti Putra Malaysia Serdang Campus, Selangor, MALAYSIA were tested for its soil resistivity. This is meant for grounding system installations with new natural enhancement material mixtures in the vicinity of vertical ground conductors. Site 2 with high resistivity and most homogeneous soil would be chosen to test the grounding system installations, while Site 1 with the lowest soil resistivity would be installed with Reference grounding system as comparison purposes. Note that a Reference grounding system is installed without any natural enhancement material mixture in the vicinity of the vertical ground conductor.