Modernization of the Mehrum Nord Transmission Network Enhances Supply Reliability

For the modernization of the transmission grid, VESCON Energy was commissioned with the new construction as well as the reconstruction of the 380/220kV substation Mehrum Nord.

By constructing the 380-kilovolt line, VESCON Energy has created a stable infrastructure for efficient energy distribution and transmission, as well as facilitating the increased utilization of renewable energy sources. This groundbreaking project for a more sustainable future was divided into two phases, A and B.

Section A | New 380/220kV substation Mehrum-Nord

In this initial project phase, a state-of-the-art 380/220 kV switchgear with a total of 11 bays was constructed:

• 2 sets of 380 kV transfer bars over 11 bays for increased flexibility.
• 1 x 2-bay 380 kV transverse coupling for optimal connection to other facility components.
• 1 x 380 kV switchable busbar (partially constructed) for distributing energy in various directions.
• 4 x 380 kV line switching bays for controlling power flows in the network.
• 2 x 380 kV combined coupling transformer switching bays, including 380/220/30 kV transformers, to adjust voltage levels and ensure efficient transmission.
• 1 x 380 kV backup switchgear bay for redundancy in the switchgear.
• 1 x 380 kV U-busbar connection bay to link the switchyard components.
• 1 x 380 kV compensation bay to maintain stable network voltage.
• 2 x 220 kV transformer feed-in bays (cable bays) for transformer currents injection.
• 1 x Diesel Emergency Power Generator (EPG, 500 kVA) to ensure supply during power outages.
• 1 x TenneT Operations Building serving as the control and administration center of the substation.

Section B | Extension 220kV- Mehrum

In the second section of the project, the existing 220 kV Mehrum substation was converted and extended:

• 3-fold 220 kV busbar over 6 switchgear bays for efficient power distribution.
• 1 x 2-field 220 kV transverse coupling for connection to other parts of the plant.
• 2 x 220 kV cable panels for feeding transformer currents.
• 2 x 220 kV reserve bays, which do not require any removal work but serve as additional switching facilities.
• 1 x 2-SS connections to the existing plant to optimally integrate the existing systems.
• 1 x Diesel emergency generator (convert existing generator) for reliable emergency power supply.
• 1 x TenneT operations building for operational management of the expanded substation.
• 1 x 30 kV concrete station as auxiliary power supply to ensure the power supply in the substation.
• 4 x control cells for monitoring and control of the plant.

Erol Pamir
Manager VESCON Energy
Phone +49 1525 6898340
erol.pamir@vescon.com

For the renewal and adaptation at the Hardegsen substation (operation with 380 kV and 110 kV), VESCON Energy was commissioned by Avacon Netz GmbH with the entire electrical installation of the 110 kV plant for the project. The major project included the renewal of the:

• Field control technology, control cells and transformer bays
• Double busbars of the bays with busbar earthing
• Zero-busbar

Services provided by VESCON Energy:

For the primary technical construction of the high-voltage stations, the design plans and the provisional planning were further processed together with VESCON Energy. In the secondary technical expansion, the experts carried out cabling work as well as the installation and connection of all control, protection and general plant components such as auxiliary power and transmission technology. VESCON Energy installed a 110 kV switchgear with a double busbar, rebuilt the plant and created the connection to the distribution network of EAM Netz GmbH.

A solution for every scenario:

The biggest challenge in the implementation of the project has been the continuous operation of the existing plant which was already a central junction for the power supply in southern Lower Saxony. The new construction therefore had to take place without any significant interruption of the power supply.

Another challenge was the fact that two construction sites were in operation at the same time in Hardegsen: The 380 kV plant with 14 bays of TenneT and the 110 kV plant with 28 bays for Avacon Netz GmbH. Through careful planning and close communication with the client, the challenge was mastered.

After a total construction period of 3 years, the substation Hardegsen was commissioned by Avacon Netz GmbH and TenneT in December 2019.

Technical project data:

• 110 kV switchgear with 28 bays including double busbar
• 1x 110 kV coupling bays
• 8x 110 kV line bays
• 5x 110 kV transformer bays
• Rebuild own need

For the renewal of the existing 380kV switchgear at the substation Wilster-West, our long-standing client TenneT TSO GmbH has commissioned VESCON Energy with the entire electrical installation for the project. Project targets:

• Expansion of the transformation station for the feed-in of renewable energies
• Receiving and Distribution of the future transmission capacity of NordLink, SuedLink, the West Coastline, the central axis and the offshore connections in the North Sea

Services provided by VESCON Energy:

VESCON Energy initially planned the primary technology and provisional arrangements for the primary technical construction of the high and maximum voltage stations. In the secondary technical expansion, it carried out cabling work as well as the installation and connection of all control, protection and general plant components such as auxiliary power and transmission technology. A 380kV switchgear with a triple busbar, designed for up to 8,000A, was installed. The new switchgear covers an area of 18 hectares, which is the same as 25 football pitches. VESCON Energy rebuilt the plant and created the connection to the distribution network of SH-Netz with two large transformers.

A solution for every scenario:

The biggest challenge in the implementation of the project has been the continuous operation of the existing plant which was already an important north-south junction. The new construction therefore had to take place without any significant interruption of the north-south connections. Consequently, VESCON Energy initially installed several 380kV temporary installations to ensure operations without almost any interruption.

After a total construction period of 4 years, the new substation Wilster-West was commissioned by TenneT at the beginning of October 2020.

Technical project data:

• 380kV switchgear with 31 bays including triple busbar
• 2x 380kV coupling bays
• 8x 380kV line bays
• 2x 380kV cable bays
• 3x 380kV transformer bays
• 2x 380/110/30kV transformers
• 1x 380/20kV transformer
• 4 bays double 110kV busbar