The influence of DC grounding electrode on oil and gas pipeline is closely related to soil structure. Based on the electromagnetic field simulation software CDEGS, this paper establishes a circuit model considering the polarization effect at the pipeline damage point. By the simulation calculation, the influence of different soil structures, including uniform soil structure, horizontal layered soil structure and vertical layered soil structure, on the distribution of pipeline leakage current, the dividing point of leakage current, the total amount of pipeline inflow and outflow current and the maximum annual corrosion depth of pipeline are studied. Through the calculation of earth potential rise and current density above the pipeline, the influence of different soil structures on the distribution of leakage current is verified. The results show that in the uniform soil structure and horizontal layered soil structure with fixed soil resistivity in buried layer of pipeline, the larger the soil resistivity is, the greater the influence of DC grounding electrode on the pipeline is; in the horizontal layered soil structure with fixed resistivity of subsoil and vertical layered soil structure with fixed soil resistivity at DC grounding electrode side, the larger the soil resistivity is, the smaller the influence of DC grounding electrode on the pipeline is.

The 3-D method is used to calculate the ground total electric field of two crossing HVDC transmission lines. By the comparison of the calculated results and the measured data on the crossing test lines with the bundles of 4×95 mm², the method is verified. Then the 3-D method is applied to the problem of practical crossing ±800 kV UHVDC transmission lines, including the distribution analysis of the voltage gradients on the conductor surface, the ground nominal electric field and the ground total electric field. Finally, the influence of the lower conductor height and the vertical polar distance on the maximum of the ground total electric field is discussed, and the minimal values of the lower conductor height and the vertical polar distance are recommended to meet the requirement of the electricmagnetic environmental protection standards. The results and approaches can provide technical support for the design of crossing HVDC and UHVDC transmission lines.

Identifying the decisive influence factors of high voltage transmission lines on the electromagnetic scattering field of neighboring radio stations and suppressing the interference amplitude is the most effective way to solve the current transmission line passive interference problem. In order to study the decisive influencing factors of the scattering field of transmission lines in the shortwave frequency band, combined with electromagnetic scattering theory, a transmission line route-surface hybrid model is constructed. The RWG basis function and Galerkin are used to test the discrete induced current, and the scattered field is solved by the electric field integral equation. Through the correlation between the induced current of the transmission line and the scattering field, The influence of the main structural characteristics of the transmission line ground wire, line spacing, number of towers and tower height on the distribution of induced current is analyzed, and the influence factor of the electromagnetic scattering field of the transmission line is indirectly determined.The results show that the complex metal structure scatterer of the transmission tower is an important influence factor of the electromagnetic scattering field of the transmission line under electromagnetic wave.

When the electric field intensity under the high voltage AC power transmission line exceeds the standard limit, a grounded metal shielding net is usually used to reduce the electric field intensity. The paper studies the calculation method of the shielding effectiveness of the finite size metal shielding net, this method of the shielding net’s shielding effectiveness is more in line with the requirements of the actual scene. On this basis, the influence laws of different shielding net layouts, shielding conductor density and shielding conductor thickness on the shielding effectiveness are obtained. The results show that the most important factor affecting the shielding effectiveness of finite size shielding net is the density of the shielding net. The layout and the thickness of the shielding conductor have little effect on the shielding effectiveness of the shielding net. The results can provide technical support for the layout and design of the shielding net.

In order to reduce the power frequency grounding resistance, the communication base station grounding network should be bonded to the power tower grounding device to form a common grounding system. Firstly, the time domain simulation model of the common grounding system is established, and then the tower grounding union simulation model is constructed to analyze the lightning response characteristics of the tower shared with the grounding system. For the underground part, based on the numerical simulation results of the method of moments, the time domain equivalent circuit model is established by the vector fitting method, which can more accurately describe the broadband response characteristics of the common grounding system. In the frequency domain solution, a frequency sampling optimization method based on rational approximation is adopted, which can improve the calculation efficiency; for the ground part, the classical Hara multi-wave impedance tower model is adopted. The two situations of the communication room arranged root span or next to a tower are discussed respectively, the simulation results show that the maximum deviations of lightning transient overvoltages on the top and cross arm of the tower before and after communication and power grounding system sharing are small, and the tower sharing will not affect the lightning response characteristics of the tower.

The electric field of transmission lines is calculated by the charge simulation method. Considering the influence of transmission tower, the electric field of transmission lines needs to be calculated in three-dimensional space. In this scenario, if the transmission lines are segmented and the charge is calculated directly, the charge will gather at both ends of the transmission lines because the two ends of the transmission lines are suspended, which is inconsistent with the actual situation. In addition, the transmission lines will be affected by the transmission tower, which will lead to the uneven distribution of the charge. When using the charge simulation method to calculate the charge of the transmission lines, it needs a finer segment, and the amount of calculation will increase rapidly. In order to solve the electric field of the high voltage AC transmission line in this scenario and improve the calculation efficiency, this paper proposes a simplified method to reduce the number of unknowns and the amount of calculation and to eliminate the end effect of transmission lines. The transmisstion lines change and the electric field around the tower are calculated by solving the equation matrix. The correctness of this method is verified by a case. This method can be used to calculate the electric field around the transmission tower of multi-level high voltage AC transmission lines.

The ion flow field (including the total electric field and ion flow density) is an important electro-magnetic environmental factor for the design and operation of ultra high-voltage direct-current (HVDC) transmission lines. Because the overhead lines are long and pass different altitude, humidity and air quality regions, the ion flow field can be influenced by external meteorological factors such as air pressure, humidity and particulate matter, which makes the modeling and analysis of ion flow field complicated. This paper reviews the literature on the characteristics of ion flow field of HVDC transimssion lines, and analyzes the effects of altitude, humidity and particles on the ion flow field characteristics, and finally clearly points out the existing problems in the current research and the future research prospects, and are helpful to the modelling and characteristic analysis of ion flow field of HVDC transmission lines in high altitude, high humidity and high pollution areas.

The distorted electric field research of high buildings adjacent to high-voltage AC transmission lines is one of the foundations for assessing the electromagnetic environment of power transmission lines. The paper considers the characteristics of high-voltage AC power transmission lines and high buildings, and uses line element models and surface element models to simulate the charge distribution of power transmission lines and high buildings, respectively. In order to ensure that the formed potential coefficient matrix is symmetrical, the potential coefficient matrix is normalized to the element length and area, thereby, and it can simplify the solution of matrix elements and improve the accuracy of the calculation. The calculation results show that the influence of high buildings on the electric field distortion of high-voltage transmission lines presents different characteristics at different heights. Therefore, in the actual electromagnetic environment assessment, it should be analyzed separately according to specific calculation scenarios. The method proposed in this paper can be extended to the calculation and analysis of the electromagnetic environment of the whole community with a bunch of high buildings.

In order to realize resource sharing, 5G communication equipment install on transmission tower, and the influence of electric field on the position of communication equipment should be considered. For the electric field calculation at the place around the surface of the transmission tower, the direct use of the charge simulation method (CSM)will have a large error. The finite element method (FEM) can fully consider the influence of the complex structure on the electric field. However, the electric field of transmission lines is open field, and the size difference between the conductor and tower is large, the finite elements mesh division is difficult, the calculation is large and the efficiency is low. In this case, the open field is cut into a small rectangular region by combining CSM and FEM. The potential distribution on the boundary of the cuboid is calculated by the CSM. Then the potential on the boundary interface is applied to COMSOL, and the surface electric field of the tower is calculated by the FEM. The calculation method is verified by the practical case of shared transmission tower. The method can reduce the amount of FEM simulation calculation on the premise of ensuring the accuracy of calculation, and it is suitable for the calculation of electric field on the surface of each voltage level transmission tower.

The radio interference generation mechanism of AC/DC parallel transmission lines is different from that of conventional lines, so that the prediction models are either too rough and too large in error, or too complicated to be mastered by engineers. In order to take into account the accuracy of radio interference solution and engineering practicability, an error back-propagation feedforward neural network model combined with gray correlation theory is proposed. First, grey theory screening are performed of 17 impact indicators that affect radio interference, and then the obtained indicators that have a real impact on radio interference are used as input variables, and radio interference is the output variable, and the radio interference prediction is performed through the BP neural network fitting algorithm. It is verified by combining the actual measured radio interference samples of the AC/DC parallel transmission lines that have been put into operation, and the results show that the prediction accuracy of the BP neural network prediction model is improved by 13.58% compared with traditional algorithms.

The ion flow field under the UHVDC power transmission line is one of the important evaluation indicators of the electromagnetic environment. Based on the Newton-Raphson method and the upwind FEM, this paper proposes a fast and stable algorithm for solving the ion flow field. First, FEM is used to solve the Poisson’s equation, and then the space electric field information is used in upwind FEM to calculate the current continuity equation. Subsequently, an iterative convergence algorithm based on Newton-Raphson is used to update the surface charge density of the conductor. Repeated iteration of the above three parts can achieve rapid and stable convergence of the iterative process. Meanwhile, the influence law of wind speeds on the distribution of the ground total electric field and ion current density under the ±800 kV transmission line is studied in this paper. The experiment results in this paper verify the effectiveness and correctness of the algorithm. The research results show that compared with the iterative convergence control factor method and the traditional method, this algorithm is not only insensitive to the initial value of the wire surface charge density, but also has a higher rapid convergence ability. The research conclusions of this paper can improve the stable convergence ability of ion flow field calculation, and realize the fast and accurate calculation of the electromagnetic environment of UHVDC power transmission lines.

As the key equipment in the new power system, the isolated power supply transformer for DC circuit breaker needs to ensure that its surface electric field strength is within the limits of electromagnetic environment. In order to get accurate calculation results, the differences among transient electric field, electrostatic field and constant electric field are discussed, the influence of air conductivity on constant electric field through the structure of insulating material umbrella skirt is analyzed, and the principle of electric field check for AC/DC hybrid complex equipment is proposed. The electric field simulation analysis and corona check of the power supply transformer are completed. The results show that when calculating the electric field of the power supply transformer, in order to keep a margin, it is suggested to use electrostatic field to check corona inception field of conductor fittings. Constant electric field is used to design the insulation performance of insulating materials. At the same time, the influence of air conductivity should be considered, and the maximum value of the calculation result under air conductivity of 10^-16 S/m(dry) and 10^-12 S/m(wet) should be selected as the reference maximum electric field.

On-line monitoring plays a more and more important role in maintaining the safe and reliable operation of power grid. In order to supply power to on-line monitoring equipment in a convenient and efficient way, this paper presents a power tapping method to collect power from ground wires using the magnetic induction effect of transmission lines. Cases show that this power tapping method can satisfy the power demand of on-line monitoring equipment. Also, factors such as line current, length of span, grounding resistance and spatial position relationship between transmission lines and ground wires may affect the power tapping efficiency. This paper discusses on the groundwire magnetic induction power tapping scheme, which lays the foundation for further optimization and practical use of power tapping from the ground wire.

In order to study the electromagnetic radiation distribution characteristics of power line communication (PLC) system in engineering applications, electromagnetic radiation testing and simulation analysis are carried out for PLC system used in power meter reading. For the straight power lines, longitudinal distribution of PLC radiation is fluctuant, and radiated lateral attenuation is rapid with a perceived range of 100~150 m. The spatial distribution of radiation generated by crossed vertical power lines fluctuates remarkably. The simulation model of PLC is established based on method of moment. A numerical analysis method is proposed to compare the measured values of PLC radiation, the calculated values of PLC radiation and the measured values of background noise. By adjusting the model parameters, the effect law of typical influence factors on PLC radiation is obtained. It is verified by comparison and analysis with the measured data that the modeling method can effectively predict the electromagnetic radiation distribution of PLC system.

With the development of communication technology, the antenna of 5G base station is arranged near the main equipment area in the substation, which will inevitably cause electromagnetic interference to the secondary equipment in the substation. Therefore, the mechanism of electromagnetic interference from 5G base station antenna to secondary equipment in the substation analyzed in this paper, the mathematical model of radiation field of 5G base station antenna is established and its field source characterization formula deduced. Meanwhile, combined with the electromagnetic scattering theory, a mathematical model of the spatial scattering field of electrical large-scale metal equipment in substations under the radiation of 5G base station antennas is proposed. The field strength distribution experiment test of 5G antenna in Henan 500 kV Guandu Substation verifies the accuracy of the algorithm. Finally, the influence of different operating frequencies, transmission power and downtilt angles of 5G base station antennas on the electric field strength at the secondary equipment is studied. The calculation results show that the base station antenna transmitting power and downtilt angle significantly change the electric field strength at the secondary equipment, and the maximum can reach 12.92 V/m, exceeding the electromagnetic compatibility immunity threshold.