Lightning Protection of Substations and the Effects of the Frequency-Dependent Surge Impedance of Transformers

Author(s):  
Rafal Tarko ◽  
Wieslaw Nowak

The reliability of electrical power transmission and distribution depends upon the progress in the insulation coordination, which results both from the improvement of overvoltage protection methods and new constructions of electrical power devices, and from the development of the surge exposures identification, affecting the insulating system. Owing to the technical, exploitation, and economic nature, the overvoltage risk in high and extra high voltage electrical power systems has been rarely investigated, and therefore the theoretical methods of analysis are intensely developed. This especially applies to lightning overvoltages, which are analyzed using mathematical modeling and computer calculation techniques. The chapter is dedicated to the problems of voltage transients generated by lightning overvoltages in high and extra high voltage electrical power systems. Such models of electrical power lines and substations in the conditions of lightning overvoltages enable the analysis of surge risks, being a result of direct lightning strokes to the tower, ground, and phase conductors. Those models also account for the impulse electric strength of the external insulation. On the basis of mathematical models, the results of numerical simulation of overvoltage risk in selected electrical power systems have been presented. Those examples also cover optimization of the surge arresters location in electrical power substations.

Author(s):  
R Clemence Kizza ◽  
M Ghaffarian Niasar ◽  
R Nikjoo ◽  
X Wang ◽  
H Edin

<p>High voltage transients in electrical power systems are mainly caused by lightning strikes and switching operations. The high voltage transients above the basic insulation level (BIL) would degrade the electrical insulation of the equipment.<br />In this work, the effect of high voltage impulses on the trend of the surface discharge at the oil-paper interface was investigated. The partial discharge patterns were recorded by the Insulation Condition Monitoring (ICM) system. The HV impulses were generated by a standard 1.2/50 μs HV impulse generator. The measurement results presented in this paper seem to show that surface<br />discharge would cause complete breakdown (continuous flashovers) at the oil-paper interface much faster when the test sample is first aged by HV impulses compared<br />to when it is unaged.</p>


Energies ◽  
2020 ◽  
Vol 13 (2) ◽  
pp. 296 ◽  
Author(s):  
Jakub Furgał

The analysis of lightning overvoltages generated in electrical power systems has a great meaning for the designers and exploitation engineers because it creates bases for the optimization of construction overhead transmission lines and high voltage substations, reducing costs and increasing reliability of the transmission and distribution of electrical energy. Lightning overvoltages generated in electrical power systems with overhead transmission lines are a result of complex, nonlinear, and surge phenomena occurring in the structure of line towers and electrical substation when the lightning current is flowing through them. Methods of overvoltage stress analysis are intensely developed, and one of the directions is working out models of high voltage electrical devices and phenomena in electrical networks, which influence the shape and values of overvoltage risks. The model of lightning current has a significant influence on the courses of overvoltages in high voltage transmission systems. The paper is focused on the analysis of the influence of the model of lightning current making use of simulations of the shape, and maximal values of overvoltages generated in high voltage transmission systems during a direct lightning strike to the overhead lines. Two models of lightning current used in simulations with the Electromagnetic Transients Program/Alternative Transient Program (EMTP/ATP) were analyzed, i.e., the Heidler model and CIGRE (Conseil International des Grands Réseaux Électriques) model. The EMTP/ATP computer program is very often used in simulations of overvoltages in electrical networks. Unfortunately, the users get no information on the criterion to be used when selecting the model of lightning current used in the simulations. The analysis presented in the paper gives practical knowledge about the effect of the use of a particular kind of lightning current model on the results of simulations of lightning overvoltage propagation in electrical networks, overvoltage protection, as well as on theoretical and practical aspects of the insulation coordination in high voltage transmission systems.


2001 ◽  
Author(s):  
J. Schlabbach ◽  
D. Blume ◽  
T. Stephanblome

2008 ◽  
Vol 42 (6-8) ◽  
pp. 911-922 ◽  
Author(s):  
Delphine Rui ◽  
Nicolas Retière ◽  
Octavian Entcheanu

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