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Insulation level of power equipment is always dependent on the electric field intensity (EFI) on the electrode surface and in internal dielectric of power equipment. However, as we know, the EFI on the electrode surface cannot be measured so far. The method for electronic EFI measurement is proposed in this article. The physical model for the experiment with an analytical solution to EFI is designed. The EFI measurement is conducted at many different points on the metal surface of high-voltage conductor of the physical model. Combined the method of images with the electric axis method, the analytical solution of the electric field at different positions on the surface of a high-voltage conductor is obtained. Comparison between measurement results and computation results of the EFI is made. The relative error between them is less than 5%. The proposed method is verified. The proposed method of EFI in this article can be used in study of compact power equipment, online detection, state evaluation, and the study on safety and stability of power grid. [ABSTRACT FROM AUTHOR]

At present, the method of obtaining the voltage of transmission lines by using the inverse problem of the electric field is generally faced with the difficulties of solving data equations. Aiming at the above problems, the method that solves transmission wire voltage through spatial electric field integration based on D-dot sensor is proposed. In this paper, with the ground as the reference potential and the vertical line of the transmission line to the ground as the integral path, D-dot electric field sensor is applied to measure the instant electric field values of several nodes on the integral path and the transmission wire voltage is directly solved combined with Gauss–Legendre numerical integration algorithm. The Gauss–Legendre algorithm is verified by the electric field distribution data on the integration path obtained by simulation. Furthermore, the improvement of the Gauss–Legendre algorithm is realized through optimizing the integral interval so that the location of integral nodes is more reasonable. Finally, the measurement system based on LabVIEW is designed and the experiment platform of the analog transmission line is constructed. Experiment results show that the measurement method of transmission wire voltage through the improved Gauss–Legendre algorithm based on D-dot sensor owns high accuracy with an error of less than 1%. [ABSTRACT FROM AUTHOR]

In this paper, a 3-D iterative approach is presented to calculate the nonlinear ion-flow field around two cross-over HVdc transmission lines. The electric-field resulting from space charges is calculated by an integral method. An analytical formula to calculate the space charges along the electric-field lines determined by the electric field is derived based on a 3-D method of characteristics. The electric-field distribution and the space-charge distribution are calculated iteratively until a convergence is reached. Since both the electric field and the space charges are mainly calculated by analytical approaches, the approach greatly reduces the computing scale and can be used for 3-D calculation. The approach was validated by the experiment on a reduced-scale model. The ion-flow field at the crossing of two ±800-kV transmission lines was calculated with the method and discussed. [ABSTRACT FROM PUBLISHER]

Hardware designed for use on high-voltage transmission lines must be designed to be free of corona. Historically, design adequacy has been verified by testing in the laboratory. However, this is problematic because laboratory testing is done using a single-phase system and the electric fields on the surface of the hardware (the driver of corona) are different between laboratory and field environments. Using three-dimensional simulations, it is shown that this difference is significant. Hence, the use of single voltage testing is problematic. In addition, the use of a corona sphere to match laboratory conductor electric fields to those in the field does not improve the process. Furthermore, it appears feasible to replace (at least some) testing with simulation. [ABSTRACT FROM PUBLISHER]

In urban and industrial areas, a relevant presence of buried metallic objects (e.g., gas and water pipes, etc.) can be detected. Usually, these elements are imagined as widespread meshed metallic grids in a good contact with the soil. In the last years, an arising interest on their role in the identification of a global earthing system has been expressed by the scientific community. Unfortunately, the geometrical and electrical properties of this kind of buried metallic parts cannot be provided by any documentations. This is mostly due to the fact that no trustworthy schemes are provided, as the management of these metallic parts is responsibility of different companies, which have installed them during several years. In order to characterize the buried metallic elements with reference to the electrical safety issue, the main quantity of interest is their resistance to earth. With this aim, a field measurement campaign was organized and the resistance to earth of more than 800 metallic objects has been evaluated through a simplified measurement protocol. In this paper, the measurement protocol, the setup, the results, and their analysis are reported. [ABSTRACT FROM PUBLISHER]

In recent years, electrical field distribution is the area of major concern in the service life of Polymeric Insulators. Several methodologies are proposed to analyze the electrical field along the insulators both experimentally and numerically of which the former might be very time consuming requiring a number of trial-error tests to determine the optimum dimensions. The advent of super computers makes numerical analyses feasible on any complex geometry modeled in 3-D and the overall optimization techniques to control the electrical field become quite easier. However, the main drawbacks in 3-D analyses are the more computation time and memory, making it desirable to simplify the structure. Hence a methodology based on relationship between electrical field profiles of 2-D (axi-symmetry model of insulator with corona ring) and 3-D model (insulator with corona ring, tower, 3 phase hardware fittings and conductors) for a dimension and location of corona/grading rings is proposed. Based on the relationship, electrical field profiles of 3-D models are predicted for different dimension and location of rings using its equivalent 2-D model electrical field profile. Commercially available 2-D and 3-D finite element based electrostatic field computation program is used. A 220 kV suspension type I string assembly is used for this study. Later, the approach is validated for 132 kV and 400 kV insulators. The type of tower, string configuration is kept constant throughout the analyses. [ABSTRACT FROM AUTHOR]

Based on the similarity theory, a reduced-scale model is proposed to study the voltage distribution characteristics in ultrahighvoltage direct current converter transformer windings under the impulse voltage. Through comparing the distribution characteristics of electric field intensity and magnetic flux intensity of the scale model with that of the original model, the effectiveness of the reduced-scale method is verified. Furthermore, the actual production design is also considered in the model. The matrices of the inductance, capacitance, and resistance parameters for the reduced-scale model are obtained by finite element method. Then, the multi-conductor transmission line model is set up to study the propagation process of impulse voltage along the windings of the converter transformer. The voltage distribution curve is obtained under a standard lighting impulse voltage and the turn-to-turn fault is taken into consideration as well. The simulation results are the basis for the following experimental study. [ABSTRACT FROM AUTHOR]

Considerable differences exist between the energised icing process and the non‐energised icing process of conductors. The main reasons that contribute to these differences are the complex interactions between the icing process and the corona discharge. To reveal these interactions, the dynamic characteristics of the corona discharge in energised icing process have to be studied. The energised icing tests of conductors are carried out in the artificial climate chamber. The short‐term statistical characteristic and the long‐term variance trend of corona properties are obtained by using the Q–V trace method. Experimental results are analysed as well. The results indicate that the distribution of the magnitude and the power of the discharge approximately obeys the normal distribution. Also, with the accumulating of the ice, the mean values of the short‐term discharge power and the magnitude increase initially then saturation appears after the increasing period. The saturation time is related to the icing velocity of the conductor. When the electric field strength is >10 kV/cm, the icing velocity will decrease if the electric field is increased. The standard deviations of the magnitude remain in the same level when the electric field is varying. [ABSTRACT FROM AUTHOR]

In this paper, a new technique for the analysis of an earthing system is presented. The technique depends on the determination of the electric-field intensity around the earthing system and distribution of the current injected into the soil. The line integral of the electric-field intensity is used to calculate the earthing resistance. The electric-field intensity is calculated by the charge simulation method, where the locations of simulating charges are optimized by using the particle swarm optimization technique. The proposed technique is applicable to simple as well as complex earthing systems. Uniform soil and multilayer soil can be accommodated. The procedure provides accurate computation of earthing system resistance and the voltage profile. The obtained results have been validated by comparison with other analytical and numerical methods. [ABSTRACT FROM AUTHOR]