Distribution networks with a voltage of 35 kV are mostly used to supply electricity consumers located in rural areas. These networks, which mainly have overhead lines, normally function according to the radial principle, although in most cases they are closed or with two-way power. In recent years, the structure of 35 kV electric network has been changing, they are being transformed from aerial to aerial- cable due to the construction of 35 kV cable lines in rural areas, which in most cases are performed with cables with cross-linked polyethylene insulation. This results in a significant increase in capacitive earth fault current. 35 kV electrical networks operate with an isolated neutral or with a neutral grounded through a reactor, if the capacitive earth fault current in the network exceeds 10 A. Currently, if the 35 kV electric network is equipped with devices for selective shutdown of a single-phase earth fault, then compensation of the capacitive current do not perform. A change in the structure of electrical networks due to new cable lines leads to a change in network parameters, namely to an increase in their capacitive ground fault current. This affects the nature of arcing electromagnetic transients in electrical networks and the increase in the level of overvoltages during arcing of a phase to the ground.
The results of the study of computer modeling of transient processes in a specific 35 kV electrical network with an isolated neutral during single-phase arcing to the ground are presented. The maximum values of overvoltages obtained in this case exceed theoretically expected according to known theories of occurrence and development of overvoltages. The distribution of overvoltages in the network and the influence of the cable line on their multiplicity are shown.
Distribution networks with a voltage of 35 kV are mostly used to supply electricity consumers located in rural areas. These networks, which mainly have overhead lines, normally function according to the radial principle, although in most cases they are closed or with two-way power. In recent years, the structure of 35 kV electric network has been changing, they are being transformed from aerial to aerial- cable due to the construction of 35 kV cable lines in rural areas, which in most cases are performed with cables with cross-linked polyethylene insulation. This results in a significant increase in capacitive earth fault current. 35 kV electrical networks operate with an isolated neutral or with a neutral grounded through a reactor, if the capacitive earth fault current in the network exceeds 10 A. Currently, if the 35 kV electric network is equipped with devices for selective shutdown of a single-phase earth fault, then compensation of the capacitive current do not perform. A change in the structure of electrical networks due to new cable lines leads to a change in network parameters, namely to an increase in their capacitive ground fault current. This affects the nature of arcing electromagnetic transients in electrical networks and the increase in the level of overvoltages during arcing of a phase to the ground.
The results of the study of computer modeling of transient processes in a specific 35 kV electrical network with an isolated neutral during single-phase arcing to the ground are presented. The maximum values of overvoltages obtained in this case exceed theoretically expected according to known theories of occurrence and development of overvoltages. The distribution of overvoltages in the network and the influence of the cable line on their multiplicity are shown.
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