Horizon 2020 PROMOTi
Enhancement of HVDC systems to interconnect large-scale offshore wind power in the North Sea via meshed HVDC offshore networksTenneT TSO GmbH
In recent years, the realization of a meshed European offshore power grid to interconnect wind power plants via High-Voltage Direct Current (HVDC) transmission systems has widely been discussed. The project “Progress on Meshed HVDC Offshore Transmission Networks (PROMOTioN)”, which is funded by the European Union, aims to analyze technical, financial and regulatory challenges within this context identifying and developing solutions for the realization of such offshore grids. Within the project, IFHT works in close cooperation with transmission system operators, manufacturers, universities and several standardization committees on the analysis and further development of potential offshore topologies and components including converters, wind turbines, DC circuit breakers as well as protection and control systems for meshed offshore HVDC grid operation. The overall project objective is the development of a so called “Deployment Plan” outlining a framework and necessary steps towards future offshore grids.
Potentials of meshed DC grids
Nowadays, offshore wind farms are increasingly connected to the AC grid via point-to-point HVDC links. This is due to the increasing distance between newly built wind farms and the coast resulting in technical disadvantages of AC cables. Cable or converter faults within these point-to-point links lead to a permanent outage of the respective connection due to the lack of redundancy. Since maintenance periods of submarine cables depend on weather conditions, power transmission interruptions of several weeks or months may be the consequence. By connecting the wind farms to DC grids instead of point-to-point links, the power transport can be upheld even during fault conditions, if the affected segment is disconnected safely and selectively from the rest of the HVDC grid.
Focus of the investigations at IFHT
Within the project, IFHT is involved in several work packages leading two of them:
“WP2 – Grid Topology & Converters“ and “WP16 – MMC Test Bench Demonstrator“. The investigations at the institute comprise the definition of requirements for DC offshore networks including qualitative and quantitative modelling requirements, technical interoperability studies, an evaluation of the frequency support potential of meshed HVDC systems as well as the development of suitable protection and control strategies. For this purpose, existing models and concepts are analyzed, tested, enhanced and discussed in close cooperation with manufacturers and universities. Moreover, a demonstrator is set up at IFHT based on lab-scaled Modular Multilevel Converters in combination with real-time simulators and DC transmission lines allowing hardware-in-the-loop investigations of future DC systems, which are integrated into existing AC grid infrastructures.
The current investigation status can be looked up at www.promotion-offshore.net. Project-related research results, reports and upcoming informative meetings are published there on a regular basis.
This project has received funding