Impact assessment of virtual synchronous generator on the electromechanical dynamics of type 4 wind turbine generators

Abstract

The de-loaded operation of wind turbine generators (WTGs) with inertial and frequency control considerably affects the dynamics and stability of variable speed wind turbines. In this context, this work proposes a comprehensive assessment of the simultaneous impact of virtual synchronous generator and frequency controllers on the electromechanical dynamics of type 4 WTGs. The proposed power balance formulation and the performed analysis, which are the main contributions of this work, provide insight into the simultaneous impact of the inertial and frequency control on the dynamics of the wind generation unit and system frequency. The assessment has been performed by means of an analytical formulation for the power balance in the WTG, characteristic curves of the wind turbine, and non-linear time-domain simulations of two test systems. The analyses have shown that the speed and torque deviation magnitudes of the wind turbine, as well as the amount of kinetic energy released by the wind turbine, depend on the wind turbine operating point. The study has also shown that the de-loaded operation considerably increases the inertial response capability of WTGs. The integrated inertial and frequency control approach has resulted in well-behaved electromechanical dynamics for the WTG.