The frequency response that can be provided by Doubly Fed Induction Generators (DFIG) and Full Power Converters (FPC) based wind turbines during the first 30 sec after a frequency event was investigated. A simplified model, which can be used for frequency studies on a single bus equivalent of the power system, was developed. Studies were carried out on the present and projected 2020 Great Britain power systems. The frequency deviation of the GB system with and without the frequency response of the wind turbines was simulated. It was shown that variable speed wind turbines with suitable controls can make an important contribution to frequency response.

With a high penetration of wind turbines, the proportion of synchronous generation in the power system will be reduced at times, thus creating operating difficulties especially during frequency events. Therefore, it is anticipated that many grid operators will demand inertia response from wind turbines. In this article, different ways for emulating inertia response in full-rated power converter-based wind turbines equipped with permanent magnet synchronous generators are considered. Supplementary control signals are added to the controller of the wind turbine to extract stored energy from the rotating mass and DC-link capacitors. Simulations in MATLAB/Simulink show that the inertia response is improved by adding a term proportional to the rate of change of frequency and by extracting the stored energy in the DC-link capacitors.