Activation schemes of synthetic inertia controller for full converter wind turbine generators

Future power systems will be characterized by the massive deployment of high power converters for so many applications (e.g. FACTS, HVDC, energy storage systems, etc.). These devices imposes new challenges on the operation and control of power systems, especially in terms of frequency support. Power converters tend to naturally decouple the new power production units from the AC power grid, disabling natural frequency response. It is expected this situation decreases the total system inertia affecting the ability of power system to overcome system frequency´s disturbances. Wind power industry has developed several controllers to provide inertial response on wind turbines generators (WTG) enabling the frequency response: e.g. Artificial, Emulated, Simulated, or Synthetic Inertia. However, there is a clear lack of knowledge about activation scheme used for these controllers and how they work in practical manner. This paper proposes three activation schemes for synthetic inertia controller on WTG based on full rated power converters (FRC): (i) continuously acting (ii) under-frequency trigger and (iii) maximum-frequency gradient trigger. Simulations considering a test system are used for evaluation of the proposed activation schemes. The main contribution of this paper is the definition activations schemes for the synthetic inertia controller and the practical simulations results demonstrating the under-frequency trigger provides the best dynamic response in term of system frequency response.