7 November 2017 - To feed Europe’s electricity hunger with more renewable energy, wind developers will have to go farther away from shore, where wind speeds are higher and steadier. Electricity will have to run longer distances to bring offshore energy production to consumers. But an important precondition is to develop more performant electricity networks that can carry electricity for long distances without too much losses. In this context, High Voltage Direct Current (HVDC) submarine cables appear to be more efficient and cost-effective than undersea High Voltage Alternative Current (HVAC) cables. But connecting offshore wind farms with complex HVDC systems has still some risks.
Best Paths’ solution to connect offshore wind farms
To minimise these risks, Best Paths experts have built a demonstrator that will allow wind developers to conduct simulations on complex Multi-terminal HVDC systems in a laboratory environment. The main objective? To investigate the interactions of offshore wind farms with HVDC converters in Multi-Terminal Direct Current (MTDC) systems while identifying potential interoperability issues to increase performances in electricity transmission.
The demonstrator is hosted in Trondheim, in the 250 m2 facility of the Norwegian National Smart Grid Laboratory, jointly operated by SINTEF Energy Research and the Norwegian University of Science and Technology.
Best Paths partners have built three Modular Multi-Level converters of 60 kW each, having different technical specifications, to identify potential interoperability issues and thus improve performance in power transmission offshore, says Salvatore D’Arco, Senior Research Scientist at SINTEF Energy Research. Within Best Paths, the laboratory has been equipped with one wind farm emulator and four converters, connected in a MTDC grid configuration.
Demonstrator in the SINTEF Energy Research laboratory
To simulate an operating wind farm, Best Paths partners have made available two real time simulator units from the OPAL-RT company and created a new machine with a software emulating power production from an offshore wind farm in real-time. The units are connected to a grid emulator acting as an interface with the remaining electrical components.
In this setup, researchers and wind developers will be able to identify potential stability issues that could not be detected in the design phase. To ensure flexibility and allow experts to compare different settings and parameters, Best Paths partners have selected a 200 kW switching converter with six reconfigurable electrical outputs and a bandwidth of over 10 kHz as a grid emulator.
The four converters integrated in the demonstrator include one classical two-level Voltage Source Converter, currently used in older HVDC connectors for offshore wind farms, and three Modular Multi-Level converters (MMC), with a rating of 60 kVA each.
Within Best Paths, the new laboratory setup in Norway will be used to validate different simulation models for offshore wind farms grid integration using HVDC links, before their actual application in the grids, which connect Danish offshore wind farms. At the same time, the laboratory will be opened to researchers and wind developers willing to test their own models with high-quality simulation systems and thus increase the reliability of offshore wind power all over Europe.