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This paper is focused on locating earth fault by means of short-term additional earthing of unaffected (healthy) phase and the determination of fault distance based on the distance protection principle. The functionality of above mentioned method was verified during experiments, which were performed in the actual distribution network. The results of the experiments showed that the method of additional...
This paper presents the results of the analysis of a vast fault records database. The fault records were obtained during numerous experiments performed from 2005 to 2011 in real resonant-earthed distribution networks. The purpose of these experiments was to provide data either for verifying distribution network safety during earth faults or for testing methods of earth fault location or elimination...
Distribution system operator (DSO) sometimes needs to operate the large network which means operating of the network with big capacitive current (in Czech Republic more than 800A). This operation puts the emphasis not only on the setting of the earth fault relays but on the safety of the point of fault too. The paper describes the theoretical analysis, simulation and tests in real compensated distribution...
This paper summarizes the main results of a study aimed at problem of the operation of the overhead line with inserted underground cable. Firstly the analysis of the risk of the cable insulation fault is presented and the study of protection applications follows. This study considers the situation of two cable sections inserted in an overhead line that is protected by surge arresters at both ends...
The MV compensated Networks in Czech Republic are operated as nonsymmetrical, that means as networks with non-transposed lines. In these networks the fault currents depend on the affected phase because the Petersen coil is tuned only for one value of earth current. The paper deals with influence of fault type on size of fault current and on the length of its transient phenomena. There are described...
The compensated networks are affected by the phase capacity asymmetry of wiring, which causes the unbalancing of the phase voltages in the tuned condition of the arc-suppression coil. In the especially unfavourable cases this effect reduces the possibility of network operation with the tuned arc-suppression coil. The operation with the arc-suppression coil out of tune is accompanied by higher values...
The paper deals with the problem of network voltage distortion due to harmonics injected into the network by wind power plant generators. The existing methodology for assessing the impact of wind power plants on a distribution network offers different approaches to analyzing the level of generated harmonics. The variability of the approach is given by the extent of the simplification of the mathematical...
Certain sophisticated digital relays offer the possibility of protecting cables by means of a thermal model with parameter setting using the knowledge of the cable heating time constant and given operating conditions. The principle of the thermal model is based on the theory of heating up a conductor by the flowing current and therefore it is necessary to know to what extent the theory is respected...
The MV networks are not construct as transposed that means they are non-symmetrical. This factor causes the unbalancing of the phase voltages and the zero component of voltage appears there. The distribution networks with overhead lines are operated as compensated with the arc-suppression coil connected to node of transformer. The operation with the arc-suppression coil out of tune is accompanied...
The compensated networks are affected by the phase capacity asymmetry of wiring, which causes the unbalancing of the phase voltages in the tuned condition of the arc-suppression coil. In the especially unfavourable cases this effect reduces the possibility of network operation with the tuned arc-suppression coil. The operation with the arc-suppression coil out of tune is accompanied by higher values...
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