This paper deals with modelling and analyzing specific transient states of voltages (i.e., of lightning surges in electric power systems of high voltages). The lightning surges arriving in a substation are impacted by more complicated wave effects. Those effects result from a complex spatial structure of each substation, and are determined by all equipment units mounted on it. A model of an electric power line and substation developed for computer software Electromagnetic Transients Program-Alternative Transients Program is presented in this paper. This model includes wave effects and nonlinear effects. It is based on a set of appropriately connected elements (i.e., distributed parameter elements and lumped parameter elements). Furthermore, the analysis results of lightning surges as well as the optimization results of a surge protection system installed in a 110-kV substation are presented in this paper.

In this paper, the effectiveness of lightning overvoltage protection of cables in high voltage overhead cable lines has been analyzed. Because of the high overvoltage level, the cables are protected by surge arresters and by metallic sheath earthing. However, in practice, quite a lot of cases of electricity-evoked damage to the cable outer sheaths are observed, proving that the effectiveness of the protection used is insufficient. As a result, the cables are exposed to environmental factors, especially moisture penetration, which contributes to cable degradation. To explain the causes of this situation, simulation studies were carried out to determine the relevant factors affecting the level of expected overvoltages. The circuit-field model of the overhead cable line in EMTP-ATP, COMSOL and MATLAB software was used for determining overvoltages on the main cable insulation and the outer protective sheath. The studies reveal that the efficiency of the cable insulation overvoltage protection is ensured regardless of the lightning strike location and the crest value of its current. However, the obtained results confirm that no matter the applied protection, the cable outer sheaths may be exposed to overvoltages with higher values than those of the main insulation. Although the analysis was performed for 110 kV lines, the conclusions are general and are also applicable to power lines with higher rated voltages.

The development of power networks encounters numerous problems. On one hand, they result from the high cost of land lots and difficulties in acquiring them from the proprietors. On the other hand, there are technical obstacles related to the constructing lines between new power sources (e.g. wind farms) and power systems. Wind farms are frequently localised in areas where the power network is poorly developed. These difficulties necessitate specific ways in which wind farms can be connected with the existing power systems. One of them lies in locating new lines within the existing line right of way. Owing to the electromagnetic impact between the lines such solutions are not frequent. Too long close‐proximity sections are avoided to reduce the consequences this impact. This study is devoted to the influence of high‐voltage transmission lines on other power lines. The localisation options in a 400 kV line right of way are analysed. The construction process and further exploitation of a 110 kV line in normal and short‐circuit conditions of a 400 kV line are presented. The prospective touch voltages and body currents are determined for these conditions.

The growing interest in the negative environmental impact of overhead power lines of high and extra-high voltage stems from the increasing ecological awareness of societies. Consequently, a number of respective legal restrictions have been issued and actions have been undertaken to reduce this impact, especially in the electric field of the power frequency. The aim of this paper is to analyze the possibilities of reducing the width of electric field influence zones by changing the design parameters of power lines and defining the spatial distribution of its conductors. This analysis was carried out using the developed and experimentally verified models for determining the electric field and audible noise in the power line environment. The computational models were used to analyze the width of the electric field influence zones of 400 kV lines and the noise levels at the borders of these zones. The research focused on single and double circuit 400 kV power lines. It was revealed that a reduction in electric field emissions is accompanied by an increase in noise emission. However, the analyses confirmed that the width of the electric field influence zones can be significantly reduced if the most important design and construction parameters of the line are properly selected. The obtained conclusions are valid not only for 400 kV lines, but also set directions to follow when changing the parameters of high voltage transmission lines of other rated voltages (above 100 kV).

The main cause of temporary overvoltages is earth faults. The reduction of such overvoltages is achieved by effective earthing of the neutral. It is assumed that the system is effectively earthed if the relative temporary overvoltage values caused by earth faults do not exceed the established limit value of 1.4 pu. It is believed that the effectiveness of earthing will be assured when, for all system conditions, the ratio of the zero‐sequence reactance to the positive‐sequence reactance is positive and ≤3, and the ratio of zero‐sequence resistance to positive‐sequence reactance is positive and <1. However, it appears that, despite the fulfilment of these conditions, a single line‐to‐earth short‐circuit can cause overvoltage exceeding by far the value of 1.4 pu. Such a situation may occur for a disturbance in the form of a single‐phase break and earth fault in a power system. This article presents models and results of simulation tests, which allowed for a comprehensive description of those disturbances both in idealised and real systems. Furthermore, the authors suggest solutions to mitigate those severe overvoltages.

Ferroresonance in power networks is a dangerous phenomenon, which may result in overcurrents and overvoltages, causing damage to power equipment and the faulty operation of protection systems. For this reason, the possibility of the occurrence of ferroresonance has to be identified, and adequate methods need to be incorporated to eliminate or reduce its effects. The aim of this paper is to evaluate the effectiveness of ferroresonance damping in auxiliary power systems of high-voltage substations by selected damping devices. Laboratory experiments, the results of which created bases for the development of models of selected damping devices, are presented. These models were used to simulate the effectiveness of ferroresonance damping in an auxiliary power system of a 220/110 kV substation in the EMTP-ATP program. The analyses showed that control systems with different algorithms of operation are used in damping devices. This knowledge is important when selecting parameters and settings of the applied damping devices for a given network and the disturbances in it. The presented research results have proved the effectiveness of commercially available damping devices, provided their parameters are correctly coordinated with the settings of the power system protection.