December 14, 2018
3 min read

World’s most powerful variable shunt reactor successfully tested

Once again, Siemens has proven its strength in innovation and expertise in shunt reactor technology. The world’s largest-ever variable shunt reactor, manufactured at the Siemens transformer plant in Nuremberg, was successfully tested recently. The powerful shunt reactor features a rating of 120–300 MVAr and a rated voltage of 220 kV. It weighs 317 tons and measures roughly 10 x 8.5 x 8 meters.

Siemens will deliver three units of this type for Hornsea Project One in the UK. Project One is the largest of four wind farms that are going to be built by Dong Energy in the Hornsea Zone in the North Sea, 120 kilometers off the Yorkshire coast – and it’s the world’s largest and most powerful wind farm so far: 174 Siemens SWT 7.0-154 wind turbines will be erected in an area of approximately 407 square kilometers. Once fully commissioned in 2020, they will generate 1,218 MW of clean power. Altogether, the four Hornsea projects will boast a capacity of approximately 6,000 MW.

With a total cable length of 900 kilometers, Hornsea Project One will also include the longest-ever offshore wind farm high-voltage AC electrical system in the world. The variable shunt reactors from Siemens will be installed onshore to support this enormous system.

With this project, the Siemens engineers yet again underlined their expertise in the further development of variable shunt reactor technology. To meet the demand for sustainability, the variable shunt reactors for Hornsea Project One were designed to achieve the lowest possible losses for such a size of machinery. The relatively low sound emissions of less than 84 dB(A) at 300 MVAr also adds to the environmental compatibility of the units.

“The 220-kV, 120–300-MVAr variable shunt reactors will cater for the fluctuating demand of reactive power compensation, resulting from the volatile nature of wind power, for the world’s largest offshore wind farm. Currently, there are only a few factories in the world that can design, manufacture, and test a reactor of this size, and we recognize the Siemens team’s excellent performance,” says Shihabudheen Kavungal Kolparambath, Project Manager at Dong Energy.

Siemens has pioneered the development of variable shunt reactors, which are ideally suited to support the connection of wind farms to existing power grids. By combining the proven design of shunt reactors with the reliability of tap changers, variable shunt reactors can keep the voltage within the defined voltage band, even when extreme voltage fluctuations occur. This enables grid operators to adapt to the reactive power currently needed and to minimize losses.

“Wind power has become a main pillar within Europe’s energy mix. However, for our customers this means a challenge in terms of grid stability and efficiency. We are proud to develop and deliver innovative products, such as this extraordinary variable shunt reactor, that increase security and enable the reliable operation of future modern power grids,” says Dr. Beatrix Natter, CEO of the Siemens Transformers business unit.