Fast-frequency response from wind generators ‒ Empirical data from a Type 4 wind farm

Grid stability is an important consideration as inverter-based generators replace synchronous generators. Primary frequency response is one part of grid stability and counters rapid grid frequency changes. Synchronous generators achieve this via electromechanical coupling between the machine stator and the mechanical inertia of the rotor. Advances in power converter technology enable inverter-based generators to contribute to stability in a similar ‒ although not identical manner and provide fast-frequency response that is a component of primary frequency response. An important benefit is that converters provide a tunable response ‒ something not possible with synchronous generators. Wind turbines with full converters are able to extract some rotational kinetic energy from their spinning rotors and deliver it to the grid as electrical energy. This work documents and analyses the ability of full-converter wind turbines to provide fast-frequency response. We use a 50.6 MW, transmission connected wind farm and inject an artificial frequency signal with a sudden frequency dip. The wind farm remains connected to the grid as the fast-frequency response is triggered and rotor kinetic energy is converted into electrical energy. We repeat this at different power levels, gather high-frequency data and measure parameters such as response rise time, peak power boost and injected energy. We find that the resulting response aligns well with expectations although prevailing wind speeds influence performance in some instances.