High Voltage DC is the key to a new era of energy. This is what we believe at Elnos, and that’s why we’re always challenging ourselves to be part fo building the best HVDC projects in the world. This is our new HVDC task.

As masterpieces of new generation technology, HVDC interconnections have an increasingly important role in shaping the power networks of the future. Their construction is one of the greatest challenges of the energy transition.
Our new HVDC task of the year is construction of HVDC interconnection DolWin 5 that will connect a new offshore wind park Borkum Riffgrund 3 to the high-voltage network on German shores.

THE THIRD HVDC CHALENGE FOR ELNOS GROUP

After completion of works on two important HVDC projects, last summer we dived into our third endeavor of this type – construction of DolWin 5, a 130 km long HVDC interconnection with a future capacity of 900 MW. The focus of our works rests on a converter station Emden in Germany, with 900 MW of installed power and +/- 320 kV DC voltage level. As a subcontractor of the company Hitachi Energy, we are performing overall electrical assembly works. It is precisely between this converter station and offshore wind park Borkum Riffgrund 3 that the DolWin 5 interconnection is being built. This is the first time we are performing works on a converter station in Germany, a country known for its highly demanding market. The equipment being installed in these stations is significantly larger and much more complex and sensitive compared to the equipment used in conventional AC stations. However, new challenges are imminent when you participate in construction of one more power network for a new generation. Such projects require a different approach to planning, execution and monitoring of works.

“It took us several months to prepare the design documentation. This was an astonishingly extensive task. Yet, a large-scale logistics operation was running simultaneously with the design process, together with the procurement of new equipment for this project. We really prepared ourselves well for this project and were eager to further expand our previously gained experience and knowledge“, said Milenko Jajčanin, Elnos Group Engineer and Site Manager on this project.

Our part of works on construction of this converter station is to perform overall electrical assembly works that include installation of all equipment necessary for its operation, protection and control cabinets, cable trays and control and monitoring system. The works also include laying and connection of MV and LV cables, measurement cables and control and signal cables as well as equipment testing and partial support during commissioning.

“Our works commenced in October 2022. The converter station is located in Lower Saxony, a region in the northern part of Germany. This part of the country is known for its rainy weather and strong winds. Such circumstances can in no way make your job any easier. Also, occupational health and safety and environmental requirements are set quite high. Works are being executed professionally and with the highest level of discipline, all in line with the daily time schedule“, said Jajčanin.

BELOW SEA LEVEL

The converter station is being built on a location below sea level. This part of soil had been won by its residents in a relentless battle fought with the North Sea. A large embankment had been constructed to separate the land from the shore. The construction site is enormous. It spreads over an area of 20.000 m2. Approximately 100 people work on this site every day, 30 of which belong to Elnos teams.

MODERN TECHNOLOGIES

Our teams are exceptionally motivated, despite the fact that this is the third HVDC project for our company. This is mainly because this project offers something new.

The teams are most fascinated by the technology which is completely different compared to typical stations. These systems imply use of electronic components for extremely high voltage levels. We took the same approach to the works as in Norway and Montenegro and we are happy to be able to prove our readiness and ability to meet new challenges posed by HVDC interconnection construction projects.

“Although we have experience with HVDC technologies, they still remain a big challenge. I would like to emphasize that this project implies use of converter modules of the fifth generation which have to be installed using custom-made tools. To meet the needs of this project we procured a machine to supply the device with SF6 gas as well as an SF6 gas quality analyzer. Namely, in order to be functional, high-voltage switches must have SF6 gas in them. With the aim to avoid potential damage during transport, HV switches are being delivered to us without the gas. Once they are installed we use our new machines to fill them with SF6 gas“, said Jajčanin.

A EUROPEAN TEAM FOR HVDC PROJECTS

DolWin 5 is an important step forward in development of an integrated European energy market. This interconnection will transmit electrical power in a capacity of 900 MW, with zero carbon transmission, which is enough energy to supply approximately one million households.

The works we are performing will last until June 2023. We are proud of the fact that the project is being executed on a very high technical level and that our employees are becoming a European team for HVDC projects.

OUR HVDC EXPERIENCE

HVDC technologies offer indispensable flexibility to the energy markets, which represents a key answer to the problem of constantly increasing demand for electrical power. These technologies significantly minimize losses during long-distance transmission and are thus becoming a global power solution. Constructing an HVDC interconnection is one of the greatest challenges of this dynamic trend. So far, our teams have been a part of two big European HVDC projects: MONITA interconnection – a power bridge between Montenegro and Italy and NordLink – the greatest European HVDC interconnection between Germany and Norway.

A TYPICAL DAY AT WORK

Every day is a new mission that starts in the early morning when daily tasks are assigned. Then, the works commence and the construction site starts looking like a giant bee hive. It is only during the midday break when everything is still for an hour. When the break is finished, everybody returns to their work until the end of the work day at about 17 h.

GERMANY – A GREEN ENERGY FORCE

The aim of the German energy policy is to get 65 percent of energy from renewable sources until the year 2030. The fast-growing clean energy trend in this country is mainly based on an ever-increasing number of offshore wind parks being constructed on the North Sea area. In only ten years, the production of energy from wind power in the sea increased from zero to 6.382 MW. This makes Germany the world’s second largest producer of this type of energy.