HV Onshore Afrati-Avlida project

Afrati-Avlida, Greece

400 kV High Voltage underground project - 80 km total length

Key Facts

Client

Public Power Corporation SA (PPC)

Total cable route length

13.5 km

Location of the project

Chalcis (Chalkida), Euboea, Greece

Duration

2010 - 2013

Quantity of order

400 kV cable system with a 1,200 A (830 MVA) capacity per circuit

Scope

  • Complete cable system, including 80 km of 400 kV 1x2,000 mm² copper XLPE cable with APL and approximately 16 km of fibre optic cable.
  • Design and engineering.
  • Manufacture and project management.
  • Tailor-made logistical concept and civil works including horizontal drilling.
  • Efficient installation performance including 90 straight joints and 12 terminations and final testing.

The project

The Aliveri power plant on the island of Euboea was to be interconnected with the mainland grid.

The project was very important for the Greek electrical grid and the regional development programme. Two parallel 400 kV (kilovolt) underground cable circuits were to interconnect the Aliveri combined-cycle thermal plant on Euboea with the continental transmission grid.

The new gas-fired plant replaced the previous fuel-oil and lignite-fired capacity, thereby helping reduce pollution, especially CO2 (carbon dioxide) emissions. It contributed to present and future requirements for electricity throughout Greece by replacing withdrawn capacity with a new enhanced capacity that could keep pace with growing consumer demand.

The project was originally commissioned by Public Power Corporation S.A. (PPC), Greece’s biggest power company. It was to be undertaken about 80 km from Athens and then handed over to ADMIE, S.A.

There were, however, significant technical challenges. One of them was a submarine section at the Chalcis Suspension Bridge, which required several long drillings beneath the seabed. Another customer requirement was that the first circuit be put into service as soon as possible, to ensure continuous operation.

In 2010 NKT received the order to create the transmission link to Greece’s second-largest island.

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The solution

NKT provided everything from an efficient cable system to horizontal drilling under the seabed.

The turnkey solution included design and engineering, as well as production of cable for one of the circuits and all accessories for both circuits. The full range of civil works, including drilling underneath the channel between the mainland and the island, cable-laying and installation, were part of our scope in cooperation with local partners. We were also responsible for project management, installation of accessories and the final commissioning tests.

We cooperated successfully with the customer and local companies, and provided a tailor-made logistical concept that would work efficiently despite dense tourism and heavy traffic in the area. We also developed a specific method to enable continuous installation work without disruption on the second circuit while it was under the inductive influence of the first circuit.

As always, NKT prioritised safety and adapted to the specific project requirements. The wellcoordinated efforts and efficient performance of our teams made it possible to finalise the project on time and to the correct quality standards.

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