DC will forecast and trade 294MW of electricity produced from the site in the North Sea, off the coast of Scotland.
"The PPA is Danske Commodities' first long-term balancing contract in the UK market, where it has been trading power since 2010," according to DC.
Beatrice is owned by SSE (50%), Copenhagen Infrastructure Partners (25%) and Repsol (25%).
It was awarded a Final Investment Decision (FID)-enabling Contract for Difference subsidy by the UK government in April 2015.
A FID is still pending, but one is due in early 2016, according to WPO Intelligence, the research and data division of Windpower Offshore. The project is expected online by 2020.