Construction of the 400 kV line from the 400/110 kV Czarna substation to the 220/110 kV Polkowice substation, including the extension of the Polkowice substation with a 400 kV switching station and the extension of the Czarna substation
The subject of the order is the comprehensive construction of a two-circuit 400 kV overhead electrical power line and optical fibre ducts from 400/110 kV Czarna station to 220/110 kV Polkowice station and modernisation of these stations.
For the construction of the overhead 400 kV Czarna–Polkowice line it is necessary to refurbish the existing 400 kV switching station in the 400/110 kV Czarna substation and construction of a new 400 kV switchyard in the 220/110 kV Polkowice substation.
The 400 kV Czarna–Polkowice electrical power line will improve the region power supply security, connecting two following substations:
- Czarna, that make it possible to transfer power to other substations, and where the works include disassembly of old facilities and installation of modern ones in the switching station; in fact it may be considered as construction of a completely new object;
- Polkowice, where 400 kV voltage is transformed into 220 kV for the transmission network and into 110 kV of the distribution network, what should significantly strengthen the power supply. In this substation will also be installed a GIS-technology 6-bay 400 kV switching station.
The line will be routed through the following communities:
- the town of Polkowice.
The line will consist of about 24 km long section of two-circuit, 400 kV three-conductor bundle (3 × AFL-8: 350 mm2) overhead power transmission line with two ground conductor OPGW wires incorporating 24 fibre optic cables from 400/110 kV Czarna substation to 220/110 kV Polkowice substation.
Some additional difficulties have been associated with the project, demanding from the contractor substantial skills and knowledge, such as need to route some sections over a forest, or over some crossing objects like roads, buildings or other electrical power lines, and through non-standard terrain conditions i.e. water reservoirs and rivers, enforcing the construction of very long spans.
The arrangement of all formal and legal issues necessary to perform the project, including all legally required permits and decisions, was commenced in July 2013, while the construction works started in September 2016. The project completion is planned for 2017.