HVDC links in offshore wind farms and offshore interconnections

The aim of this demonstration is to reduce the risks of HVDC links connecting offshore wind farms and to foster new suppliers and sub-suppliers of HVDC technology. This will be done by investigating the interactions of the converters in the wind turbines and the HVDC substation, and by developing a testing laboratory where different stakeholders can perform their studies in a real environment with real measurements from converter equipment.

The demonstration consists of two parts: the first part focuses on developing software models of all of the main pieces of equipment in a HVDC link and run simulations on different topologies that range from point-to-point links to meshed HVDC grids. In order to study a complete HVDC system both averaged and switched models will be developed. These include: wind turbine (full-converter and with both AC and DC output in the medium voltage side), DC/DC converter, VSC (two-level, half-bridge MMC and full-bridge MMC), HVDC converter station and cable and AC grid. 

The second part of the project will be focused on building a DC demonstrator in the testing facilities owned by SINTEF Energy Research in Norway. The tests performed in this demonstrator will have the objective of validating the simulation models developed in the first stage of Demo 1. The existing laboratory infrastructure will be upgraded with three different converter prototypes in the 50 kW power range designed to emulate the existing MMC converter technologies (full-bridge and half-bridge in different configurations). 

Finally, the results and lessons learned will be applied in a simulation of the East Anglia project -an area of 7.2 GW of wind capacity in the UK that was awarded to the joint venture between ScottishPower Renewables and Vattenfall Wind Power.

Enabling stakeholders other than big HVDC equipment manufacturers to have access to a scaled-down demonstrator and open simulation models will foster new suppliers and sub-suppliers of HVDC equipment, and allow new entrants to gain access to the technology. Additionally, the cost of the technology will be lowered once a greater level of competition is achieved. This will facilitate development of offshore wind farm projects that are currently not attractive from the economic point of view, thus increasing the penetration of wind energy generation in the European system. The results from the demonstration will shed some light on the most suitable network topologies to interconnect the large offshore wind farms that will be built in the future.

Iberdrola, Cardiff University, SINTEF, Univesity of Strathclyde, Gamesa, Tecnalia, RSE, Energinet.dk

Diagram of demonstrator system