Offshore Transformer Module – AC Grid Access

Table of Contents

AC Grid Access Solution

Offshore Transformer Module


AC transmission is the most extensively used technology for connecting offshore wind farms. Since 2008, Siemens’ 10 offshore platforms have been contracted for, and those completed have been successfully delivered. Unlocking the potential for offshore wind power in the wider energy mix continues to be dependent upon being able to improve and minimize the levelized energy cost.

Siemens has taken the lead in utilizing its experience in generation and grid access to improve its portfolio. This innovation allows the company to reduce both operational and capital expenses, meaning the company is on track to assist their customers in achieving the goal of minimizing the levelized energy cost to €0.10/kilowatt by 2020.

AC Grid Access Solution

The company’s new innovative solution is founded on the concept of two smaller and much lighter platform modules to substitute the single large platforms that are currently deployed. This new solution facilitates the connection of the similar rated power in total. It also provides high flexibility by enabling the modules to be set up and incorporated with the wind turbine foundation or independently based on the requirements of customers.

The new AC grid access solution has several options that can be deployed to meet the requirements of each project while keeping the optimized price level required by the market.

New AC grid access solution – saving space, weight and costs by:

  • Fire safe and environment-friendly by deploying MIDEL technology
  • Ability to integrate with the turbine foundation or to be deployed separately
  • Rugged and simple design
  • Installation through foundation/turbine installation vessels
  • Modular approach to improve availability, operational performance and maintenance
  • Electrical components optimized from the company’s accumulated life cycle experience

AC Grid Access Solution

Allowing for the transmission of the same amount of power than a conventional large platform, Siemens’ new AC grid access solution uses two smaller, substantially lighter modules. Allowing both independent installation of these modules or integration with the wind turbines’ foundations, the new solution provides a new level of flexibility. Further technical options ensure optimal adaptation to individual requirements at optimized cost, which helps lower the levelized cost of energy.

Considering the wind farm as a holistic asset, Siemens designed the new AC grid access solution. By doing so, the company can utilize synergies to make sure that the lowest cost solution can be achieved for the grid access. By completely utilizing the wind farm’s potential as an integrated system, the company will be able to leverage the following:

  • Using the wind turbines to offer reactive power, thus eliminating the need for offshore reactors
  • Employing wind turbine tower emergency refuge and heli-hoist to reduce equipment and servicing requirements
  • Using end-of-array connections to offer flexibility and eliminate the need for diesel generators
AC grid access, general data
Rated power (MW) 250
Rated HVAC voltage (kV) 220
Rated MVAC voltage (kV) 33 or 66
Platform weight (t) 652



This information has been sourced, reviewed and adapted from materials provided by MIDEL.

For more information on this source, please visit MIDEL.

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