Kompenzace zemních spojení ve vn sítích.

Abstract

The aim of this paper is to describe the topic of earth fault in three phase MV network which is used to distribute electrical energy, especially at the level of 22 kV. I focus on the description of transmission parametres, which are essential for understanding the topic of this paper. I look at the description of different kinds of cabel and outside transmission throughout the voltage levels. In connection to the theoretical foundation, I describe the main principles of the different ways of maintaining network, with consideration of the formation of nodes and earthing of the network’s inanimate parts. Following with the description of theoretical formation of earth fault in network and in which networks earth fault could be found. Each state which happens during earth fault is characterized according to the formation of the node in the isolated network. Except for the theoretical aspects, I also include phasor diagrams which are depicting relevant aspects. Earth fault is already an interesting term itself. Furthermore this topic includes the vast problematics of the physical, energical and safety character, which is why this topic needs to be looked at comprehensively. In the next part of this paper, I will be discussing the basic description of localization of earth fault in network. As a part of my paper, I have conducted an analysis of the development of capacitive currents in the distribution system E.ON Distribuce, a.s. The result of this analysis is a graph showing the trend of development of capacitive currents. In the last chapter I focus on the calculation of characteristic values of earth fault in designed IT network with earthed node through compensation reactor. I propose a suitable compensation reactor for this network. The main aim of this paper is to summarize the theoretical and practical knowledge in order to understand earth fault the way of its compensation and the possibility of its exact localization. To create the illustration schemes I have used the licensed program AutoCAD.