WindFlag, a collaboration between four universities and two companies from Denmark and Turkey, plans to apply microgrid principles to improve the integration of offshore wind farms with the electricity grid in Turkey.
Turkey is home to one of the fastest growing energy markets. There are plans in place to increase electricity generation from offshore wind farms, but their intermittent nature poses an integration challenge with the country’s existing power system.
At the moment, traditional power plants set the electricity system’s operating parameters, such as voltage and frequency. Wind farms inject power when it is needed, but have little responsibility for providing grid support services to maintain those parameters.
“If the grid has some failures, they disconnect because they can’t operate like a power plant,” said Josep Guerrero, Villum Investigator at the Center for Research on Microgrids, Department of Energy Technology, Aalborg University. He is the project manager and one of the Danish project partners.
“The future of offshore wind should be supporting voltage and frequency, this is one of our targets.”
From passive to active participant
The WindFlag team plans to apply established control strategies developed for microgrids to offshore wind. The intention is to turn offshore wind farms from a passive to an active participant in the energy system. As well providing power, they will support the grid with maintenance of good power quality. By adding energy storage systems, wind farms can also assist with black starts — the restart of the power system after a complete shutdown, a task now carried out by fossil fueled generators.
“If we use microgrid technologies, we can ramp up and have a black start of the wind farm without needing diesel generators,” Guerrero explained.
If the harmonics content, one of the variables of power quality, becomes too high for an offshore wind farm, it disconnects from the main grid. The WindFlag team plans to take existing methods from microgrids to manage harmonics issues at the point of common coupling to prevent disconnection.
“Our idea here is that, beyond adding filters, every converter from each wind turbine will be coordinated to compensate the harmonics at the point of common coupling,” Guerrero explained that this would be achieved with two levels of control. “The primary control takes care of each of the units, and the secondary level takes care of power quality at the point of common coupling.”
Operating in island mode
Another idea borrowed from microgrids involves running wind farms in island mode. This can be beneficial, if for example, a wind farm requires unexpected maintenance on its export cable. This would result in the shutdown of the wind farm, and a lengthy re-start once the repairs are completed. If, however, the wind farm continues to run on minimum load in island mode during the repairs, bringing it back online is faster once the export cable is re-connected.
This project is currently in the initial planning phase. One of the challenges will be scaling up the microgrid principles from the proven kilowatt scale into the megawatt scale. Once the project is complete, its results could travel beyond Turkey’s energy market, benefiting others with plans to ramp up electricity production from offshore wind.
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