Dynamic frequency support with DFIG wind turbines — A system study

Frequency control in interconnected electrical power systems is nowadays realized using the networks' conventional thermal power plants. With the ongoing changes in power systems worldwide the share of these conventional power plants is decreasing while renewable resources such as wind power and photovoltaics are increasing their share continuously. Up to now a contribution of renewable sources to primary frequency control is not realized in interconnected power systems. This paper describes possibilities to support the frequency of power systems using wind turbines with enhanced active power functionalities such as primary frequency control and synthetic inertia. The effects of these functionalities are analyzed in the IEEE 39 bus system. Different simulations with an implementation of these functionalities in a doubly fed induction generator wind turbine model show promising results. The frequency behavior of a 50 % penetrated system with standard wind power plants shows unfavorable frequency behavior compared to the original system, whereas a system with additional frequency supporting functionalities by wind power plants improves the frequency behavior significantly.