Curtailment: an option for cost-efficient integration of variable renewable generation?

According to the European Directive 2009/28/EC 1 , renewable energy systems (RES) enjoy preferential treatment in the electricity grid in so far as the secure operation of the power system permits. However, there will be times when it is not possible to accommodate all priority dispatch generation such as variable renewable generation (VRG) sources like wind and solar while maintaining the safe operation of the power system. Security-based limits have to be imposed, due to both local network and system-wide security issues. Therefore, it is necessary to reduce the output of variable renewable generators below their maximum available level on occasions when these security limits are reached. This reduction of VRG is referred to as “curtailment” and is consistent with the principle of priority dispatch.