Provision of Control Reserve by Wind Power Plants – A System Study

Abstract

The share of wind power plants of the overall installed capacity of electrical power generation is continuously rising since the last years. Nowadays, provision of ancillary services as frequency control is mainly supported by conventional power plants. However, in connection with a decreasing number of conventional power plants, wind power plants need to contribute to frequency control to a greater extend in the future.

This paper presents an analysis of the impacts of an increasing supply of control reserve by controllable wind power plants on grid performance. The grid performance is thereby measured by grid frequency response metrics after a major generation loss. The European interconnected power system is simulated with focus on the four German control areas. Providing control reserve by wind power plants can be performed by a variation of the rotor pitch angle and the tip speed ratio. A control strategy for variable speed wind turbines to supply control reserve in order to stabilize the grid frequency is presented. Comparing the frequency response metrics of the future and the present scenario, it is shown that the grid performance is equal. The maximum frequency deviation is even lower in the future scenario. A sensitivity analysis shows, that even a further decrease of rotating masses in the grid is tolerable. Apart from all these technical challenges, it needs tobe reflected that the current legal framework in Germany must be changed in order to give wind power plants the possibility to participate in the primary and secondary balancing market.