The EU member states have passed a resolution requiring one fifth of their electricity needs to be derived from renewable energy sources by 2020, with wind farms covering a large part of this requirement.
A group of European industrial companies and research organizations teamed up to investigate how wind farms on the Iberian peninsula could be safely integrated in the European electricity grid on a large scale.
To assist grid operators in the capture, control and forecasting of wind energy, the Fraunhofer Institute for Wind Energy and Energy System Technology IWES has made available both its Wind Farm Cluster Management System (WCMS) and its Wind Power Management System, adding new functions to both.
The researchers used these software packages to integrate five wind farms in Portugal with a total capacity of 204 megawatts and six in Spain with a total capacity of 107 megawatts in the power grid. The integration was achieved in real-time tests under a variety of weather conditions.
"We used the WCMS to link the scattered wind farms in a cluster, enabling them to be controlled by the central control station of the Portuguese and Spanish power utilities respectively. While the WCMS keeps both the frequency and the voltage of the electricity grid constant, thus ensuring safe operation, Fraunhofer’s Wind Power Management System forecasting software uses artificial neural networks to calculate expected wind energy on the basis of predicted weather patterns", explains Dr. Kurt Rohrig, department head at the Kassel branch of the IWES.
Individual wind farms are subject to wide fluctuations in output The more wind farms that can be interconnected in a cluster, the easier it is to balance out the fluctuations caused by variations in wind force, from gusty winds to totally calm conditions. And the higher the number of installed facilities, the lower the energy price. "The price of electricity produced using wind energy is currently seven cents per kilowatt-hour; by 2025 it should be around four cents", says Rohrig.
Fraunhofer researchers are negotiating with the Portuguese grid operator with the aim of integrating their software in the latter’s control system. And Kurt Rohrig is convinced: In the long term, wind farms will replace traditional power plants.
Said integration was experimented on the Iberian Peninsula by means of real-time tests under various weather conditions. The aim was to achieve the safest grid-integration of 11 wind farms totalizing 311 MW, of which 204 MW from 5 plants in Portugal and 107 MW from 6 wind turbines plants in Spain.
To this end, researchers from the IWES (Fraunhofer Institute for Energy and Wind Energy System Technology) have developed two specific types of software which were used to provide grid operators the information that is required to manage and estimate the output of the 11 plants.
The first one (Wind Farm Cluster Management System) was used to safely link the scattered wind farms in a cluster, monitoring both the frequency and the voltage of the electricity grid. The second one (Wind Power Management System), based on weather patterns, was used to estimate the amount of wind power that was produced and integrated moment by moment from each plant.
Integrating various wind farms not only guarantees a safe supply, but also produces advantages in terms of costs. According to researchers from the IWES, an appropriate line management of wind farms could reduce the price of the produced kWh by about 40% by 2025.