Best Paths unveils a real-time offshore wind grid simulator, Trondheim

Over 50 experts from the electricity sector came to Trondheim, Norway, on 11 May 2017 to hear the first results of BEST PATHS. The project had split its work into five demonstration areas covering the problems facing Europe’s electricity sector, from connecting renewables to repowering ageing lines and linking national grids. This first Special Stakeholder Workshop was given over to the first demonstration, which looked at problems that arise when offshore wind farms are connected to meshed High Voltage Direct Current (HVDC) grids.

Iñigo Azpiri of Iberdrola, one of the largest wind generation companies in the world and the leader of the first demonstration, explained the thinking: “With the increase of renewable energies, Direct Current has become a prominent technology because it is more efficient and reliable for transmitting power coming from remote renewable energy sources, and especially from offshore wind farms. In Best Paths, we developed an innovative set of models and a simulation toolbox that can be used to test the integration of offshore wind into an HVDC grid. This is a great development to include more renewables in our energy mix.”

A public toolbox

The models built in the first demonstration simulate how offshore wind farms behave when tied into HVDC grids. They help connect large offshore wind farms to the onshore grid and carry large amounts of electricity with minimal losses.

The project gathered the models into a simulation toolbox and released it to the public, so that researchers and offshore wind project managers could test whichever system configuration they had in mind. The partners had already run five configurations through it, from a simple point-to-point HVDC link up to a twelve-terminal HVDC system with offshore DC links. These configurations, seen as likely models for offshore wind transmission in the following years, were assessed on power quality, converter ratings, protection and faults, fault tolerance, resonance and grid code compliance, and were to be refined after laboratory tests.

Into the lab

After the workshop, participants toured the Norwegian National Smart Grid Laboratory, where the models were to be tested. The laboratory, run by SINTEF Energi and the Norwegian University of Science and Technology (NTNU), already had three modular multilevel converters of 60 kW each connected to a real-time simulation system. Power-Hardware-in-the-Loop equipment was to be added later, so that researchers and wind developers could test their models in a real laboratory setting with different grid parameters. Results of the simulations were due in December 2017.

Progress on the other four demonstrations was shown in parallel poster sessions, with full results planned for dedicated events in the first half of 2018. The speakers’ presentations from Trondheim were published by the project.

Offshore wind links of the kind modelled here are the subject of the Demonstration 1 page; a working case of offshore wind connections doubling as a cross-border link is the Kriegers Flak Combined Grid Solution, which has carried trade between Denmark and Germany since December 2020.