Virtual Inertia Control for Renewable Energy Integration Based on the Improved SOGI-FLL

The combined inertia control based on the frequency difference and frequency derivative is an effective control method for the grid-following converters to participate in the frequency regulation. The accurate detection of the frequency difference and frequency derivative is the key to improving the stability of the converts’ combined virtual inertia control. The second-order generalized integrator-based frequency-locked loop (SOGI-FLL) is able to directly detect the frequency derivative, but in the case when the harmonic content in the voltage signal is high, the detection of the frequency derivative will be interfered. Therefore, this paper proposes a virtual inertia control method based on the improved SOGI-FLL. By adding the front-end cascaded SOGI-FLL, the interference from harmonics on the frequency derivative is eliminated. In addition, the PSCAD simulation are performed to validate the proposed method.