Conference Agenda

This work provides a simplified transient model for low-voltage DIN rail surge protective devices (SPDs), accounting for their resistive, inductive, and capacitive behavior. The time-domain modeling approach is based on impulse current and sinusoidal voltage experiments. The lumped-circuit model is implemented in the ATP-EMTP environment and yields results in satisfactory agreement with the experimentally derived residual voltage and energy absorption of commercially available DIN rail SPDs for single- and three-phase installations. The proposed model can be used for evaluating the protection level and maximum residual voltage of SPDs under standard and non-standard surge currents and can be an effective tool employed in insulation coordination studies of power systems.

This paper presents a systematic investigation of equivalent homogeneous earth method (EHEM) for calculation of earth-return impedance of overhead conductors above a multi-layer earth. The recently developed EHEM is based on the concept of equivalent propagation constant of earth. The characteristics of equivalent propagation constant of earth and integrand convergences of EHEM are further studied. The parametric studies of accuracy on earth-return impedance between exact formula (EF) and EHEM are also presented in this paper.

Power systems are exposed to different types of electromagnetic transients, which involve a large spectrum of signals whose duration can range from several nanoseconds to several milliseconds, and whose peak values can also cover a wide range of values. Therefore, measuring electromagnetic transients in power systems is a challenging task. Fast front transients caused by lightning events are especially dangerous, and improved knowledge about them is essential for better protection design. The development of measuring systems for such phenomenon is important. This paper is dedicated to the development of a measuring system for lightning and line surge arrester currents. Modern electronic tools and equipment, as well as cutting-edge communication and information technologies, constitute the foundation of the proposed system. This includes the most recent models of acquisition units and GPS devices that are now available on the market, as well as communication networks including 4G, 5G, and WiFi. Software and hardware components of the system are described. The paper presents laboratory tests conceived to prove that the system operates correctly and provides accurate results. The measurements are compared to EMTP and MATLAB simulations. Both are in agreement.

A methodology is proposed for estimating the shielding failure flashover rate (SFFOR) of single-circuit overhead lines with horizontal phase configuration. An application to a 66 kV overhead line is presented. A stochastic lightning attachment model is employed, based on the concept of fractal structures, to compute the probability of shielding failure to the line. Results of stochastic modeling are combined with those of an ATP-EMTP model for estimating the critical lightning currents causing flashover of the line insulation. Shielding failure results of the proposed methodology are compared and discussed with results obtained employing the methodology of the IEEE Std 1243. Innovation of this work lies in estimating the SFFOR of overhead lines by considering the stochastic nature of lightning attachment, physical criteria associated with leader discharges’ inception and propagation, as well as electromagnetic transient simulations to predict lightning-related flashover to overhead lines accurately

This paper assesses the influence of corona effect on the overvoltages developed across the insulator strings of overhead transmission lines due to lightning. The influence of corona is investigated considering lightning strikes to the tower top and shielding wires at midspan. A large range of soil resistivity and lightning currents peaks are evaluated in the analysis, and the
stress across the insulator strings is evaluated applying the integration method. Simulations are carried out in the Alternative Transient Program (ATP/EMTP), wherein the corona effect is
represented through the accurate Suliciu corona model, which was implemented using the MODELS interface and combined with J. Marti line model. Furthermore, it was also represented the wideband behavior of tower grounding system. Results showed that corona effect has a minor influence in the overvoltages across the insulator string for strikes to the tower top. However, it strongly influences the overvoltages across line insulators ensuing from a lightning strike to the shielding wire at the midspan, leading to a decrease in the peak value of the lightning current that causes line flashover.

In mixed/Syphon connections, the cable system as a whole can be subjected to fast-front overvoltages due to lightning strikes, either directly on the phase conductors or on the shield
wires of the overhead line(s) connected to the cable. In this paper, a methodology is presented that facilitates the calculation of the failure rate performance of a cable’s sheath bonding system due to
lightning strikes on the connected overhead line(s).