Assessment of inertial potential of variable-speed wind turbines

Variable-speed wind generators are decoupled from the grid frequency by their power electronic interfaces. These generators do not naturally exhibit inertial response or any other form of frequency support in generation deficit situations. This study assesses and quantifies the capability of wind turbines with doubly-fed induction generators for emulating the inertial response of conventional generators by providing temporary extra active power on top of the available production. Special attention is given to the underproduction phase that follows overproduction due to rotor speed recovery. Results show that the inertial contribution strongly depends on the wind turbine operating conditions and the allowed underproduction level.