Fraunhofer Institute for Wind Energy SystemsAt a glance
- The accelerated expansion of the offshore wind energy sector is associated with new challenges for power grids at sea. The technical complexity and interactions between the components pose a high risk to stable offshore grid operation.
- With the aim of better understanding and minimizing said risks, a one-of-a-kind test facility for the grid integration of future turbines with a capacity of up to 30 MW is being set up as part of the ENGEL research project.
- The goal is to develop test methods and standardized processes for the connection of the wind farms to HVDC systems.
- Among other things, Fraunhofer IWES will be lending its 10 MW nacelle test bench to the project.
The challenge
Offshore wind energy is set to form a key pillar of climate-neutral power supply, and the German government is pursuing ambitious expansion goals accordingly: 30 GW are to be installed in German waters by 2030, increasing to as many as 70 GW by 2045.
However, various technical issues and the lack of a holistic grid integration process stand in the way of achieving this goal. Operation of the offshore grids at present is characterized by a lack of buffers for energy storage and low impedance between the components, resulting in strong interactions between the wind turbines themselves as well as between the wind turbines and the HVDC converters. Furthermore, technical innovations in future generations of offshore wind turbines are set to lead to higher technical complexity of the offshore energy supply systems (OESS). At the same time, there is a lack of overarching regulatory and planning processes for the operation of a stable OESS.
The solution
The ENGEL project will lay the foundations for a structured and generally applicable process for the grid connection of offshore wind farms. The first phase will see the setting up and commissioning of a one-of-a-kind testing facility specialized in the grid integration testing of offshore wind turbines with a capacity of up to 30 MW, which will realistically simulate the components of the turbines utilizing a virtual hardware in the loop (HiL) environment.
The second phase will address the expanded requirements of the Offshore Grid Code and the validation of the impedance models in accordance with the state of the art, in addition to testing methods of EMT model validation for the largest offshore wind turbines currently in operation. The third phase will involve development of a HiL framework on the basis of intelligent, component-based validation methods, with the aim of going beyond the tests on a single turbine and including the operating behavior of the real wind farm. Scenario-based tests will be employed to verify whether the behavior of the offshore turbine also corresponds to that of the model in real operation.
As the project coordinator, Fraunhofer IWES will be transferring large parts of the infrastructure of the institute’s own 10 MW nacelle test bench for further use in the ENGEL 30 MW test facility, among other things. In parallel to the project, IWES will be initiating a steering committee comprising the most important stakeholders to develop an overall process for the discussion of future requirements.
The added value
The ENGEL project will contribute to the minimization of risks in the operation of offshore energy supply systems, and thus to stable and reliable energy supply. In the future, reliable models for the planning of wind farms will be available to wind farm planners and transmission grid operators from an early stage. The steering committee will ensure that the current state of the art can be taken into consideration by all stakeholders during planning and operation. Furthermore, Fraunhofer IWES’ one-of-a-kind test field will also be available for the testing of innovative processes in the future.
