Frequency Support by Wind Power Plants in Isolated Grids with Varying Generation Mix

Increasing wind power penetration in power systems has resulted in an urgent need for the assessment of their impact on grid security. Besides the participation in voltage control, there also exists a growing interest in the delivering of other ancillary services like power-frequency control. This paper investigates further the technical feasibility of delivering frequency support with wind turbines in a small power system. Different control mechanisms are elaborated in Matlab/Simulink to deliver frequency support in the case where the turbines have a power reserve available and in the case where they are operating at maximum available power. Also the influence of the generation mix is examined. Results reveal that the displacement of conventional generation with wind power results in a deterioration of the frequency response. However, due to the implementation of the different control mechanisms presented in this paper for delivering inertial response and primary control, the frequency stability is improved.