Bornholm Island

A large-scale wind turbine on Bornholm Island

The island of Bornholm is a Danish island situated just south of Sweden that represents roughly 1% of Denmark’s population and electricity load. The OSTKRAFT Company is the utility on the island serving around 28,000 customers. The peak load on Bornholm island is around 63 MW, and annual electricity consumption in 2007 was 262 GWh. Wind power accounted for 30.2% of generation in 2007, which an above average wind penetration rate in Denmark.

Bornholm island was one of the field test sites for the European Commission’s More Microgrids project, due to its ability to go into planned island mode which makes it a good site for demonstration of new technology concepts such as how to incorporate large amounts of wind turbines during islanded operation.

The supply technologies in the Bornholm Island microgrid consists of 14 diesel generators (34 MW), 1 oil-fired steam turbine (25 MW), 1 steam turbine running off a mixture of oil, coal, wood chips (37 MW), 35 wind turbines (29 MW), and 2 biogas turbines (2 MW). The distribution network is split into a 60 kV network and 10 kV network. OSTKRAFT’s main control room for the microgrid incorporates two SCADA systems: ABB Network Manager and Vestas Online. The former system takes measurements as 10 second instantaneous values, 1 minute average values, and 1 hour average values. The latter system is used for 6 controllable wind turbines, and measurements are stored as 10 minute average values.