1. Directive 2009/28/EC of the European parliament and of the council of 23 April 2009 on the promotion of the use of energy from renewable sources and amending and subsequently repealing Directives 2001/77/EC and 2003/30/EC, 2009.
2. Review of international grid codes for wind power integration: diversity, technology and a case for global standard;Mohseni;Renew Sustain Energy Rev,2012
3. Beacon Power LLC, http://beaconpower.com/operating-plants/[accessed 06.08.2014].
4. Primary frequency regulation with Li-ion battery energy storage system: a case study for Denmark, in 2013 IEEE ECCE;Swierczynski;Asia Downunder (ECCE Asia),2013