Of particular interest within fifth generation (5G) cellular networks are the typical levels of radiofrequency (RF) electromagnetic fields (EMFs) emitted by ‘small cells’, low-power base stations, which are installed such that both workers and members of the general public can come in close proximity with them. In this study, RF-EMF measurements were performed near two 5G New Radio (NR) base stations, one with an Advanced Antenna System (AAS) capable of beamforming and the other a traditional microcell. At various positions near the base stations, with distances ranging between 0.5 m and 100 m, both the worst-case and time-averaged field levels under maximized downlink traffic load were assessed. Moreover, from these measurements, estimates were made of the typical exposures for various cases involving users and non-users. Comparison to the maximum permissible exposure limits issued by the International Commission on Non-Ionizing Radiation Protection (ICNIRP) resulted in maximum exposure ratios of 0.15 (occupational, at 0.5 m) and 0.68 (general public, at 1.3 m). The exposure of non-users was potentially much lower, depending on the activity of other users serviced by the base station and its beamforming capabilities: 5 to 30 times lower in the case of an AAS base station compared to barely lower to 30 times lower for a traditional antenna.

It is shown that the most important electrical design criteria for long (i.e., stability limited) high voltage overhead transmission lines operating at a given voltage are all related to the spatial electric field distribution between phase conductors. Hence, when designing a long transmission line, a change in one design parameter necessarily causes changes in the others. It is shown how an understanding of these relationships can lead to insight into the design and to the tradeoffs that must be made in designing these transmission lines. More specifically, a more spatially uniform electric field implies an increased power capacity for long transmission lines but also reduces the critical flashover voltage and increases the capacitance per unit length.

A simple model for coupling of an electromagnetic plane wave incident on a conductor above ground has been developed using reciprocity theory, providing some advantages as compared to the conventional transmission line approach. The model is developed using a semi-infinitely long single conductor above a lossy ground plane and connected by an arbitrary load impedance to a vertical grounding conductor. This configuration corresponds to the worst-case wave coupling, because it leads to a line induced current larger than in the cases of finite and multiconductor lines. A frequency-domain Thévenin equivalent model is developed to relate the incident wave amplitude to the voltage across a generic load, connected at any point on the vertical conductor. The application to the threat analysis of a high-altitude electromagnetic pulse impact on a power transmission line is discussed by considering the time-domain solution (via inverse Fourier transform) for an incident EMP fast-rise transient (E1) waveshape, following the standard IEC specifications. For typical high-voltage power line load impedances, it is shown that voltage magnitudes in the MV range can be induced across the line termination, in the case of a wave with a near-grazing incidence angle and with wave vector aligned along the horizontal conductor.

Power system reliability requirements necessitate the development of measurement systems to monitor the operational state of critical transmission lines. Here, a novel non-contact method for monitoring overhead transmission lines is proposed. The method is based on measuring amplitude and relative phase of the transmission line’s space potential at two or more strategically located points in space along with the use of passive phase shifters to enhance the sensitivity of the measurements. Applications of voltage unbalance and conductor sag measurements are demonstrated along with the results of conductor sag measurements on an operating 230 kV transmission line. It is shown that using enhanced relative phase measurements can significantly improve the sensitivity of the measurements.

A computationally efficient charge simulation method is developed for three-dimensional electrostatic calculations involving parallel high voltage transmission conductors near a cloud of point charges. The conductors are modeled using axial line charge density segments, each with linearly varying charge density. A typical problem involves solving for the line charge densities and point charge values given the system geometry and voltage boundary conditions. The method was developed to support ongoing research into high voltage transmission line optimization using the external electric field to link transmission capacity and switching impulse flashover. The method uses superposition and applies Fourier principles to reduce computational burden by moving portions of the problem to the spatial frequency domain. Computation time can be significantly reduced relative to an all-spatial charge simulation approach. Examples involving bundled transmission conductors show measured computation time improvement and compare space potential and electric field results to those obtained from finite element analysis.

The electromagnetic interference (EMI) generated by switching operations within high-voltage DC (HVDC) converter stations is an issue that has been addressed by CIGRE, and methods to manage EMI should be considered in the design phase using electromagnetic modeling techniques. It is shown that the methods of the moments-based techniques that have been used in many previous studies may not be sufficient. Here, a finite-difference time-domain method is used to study the properties of single switching events using a realistic model of an HVDC converter station with a special emphasis on determining the impact of the valve hall on shielding EMI. It is shown that the valve hall does not confine high-frequency electromagnetic fields to the valve hall; rather, it delays them from exiting through bushings in the wall and spreads them out in time. Further, it is shown that incorporating electromagnetic absorbing material into the valve hall’s design can significantly reduce EMI outside the converter station.