Improved Control Strategy of Virtual Synchronous Generator in Response to Power Grid Harmonics

Abstract

By virtual synchronous generator (VSG) technology, the inverter can be controlled simulating the operation characteristics of synchronous generators and regarded as an access of renewable energy. The harmonics contained in the power grid brings the same order harmonics to the grid-connected current generated by VSG, result in an increasement of harmonic content in the power grid. In order to solve this problem, an improved VSG control strategy is proposed. Firstly, the equivalent model of VSG is established. Based on the analysis of the impact of harmonics on the grid-connected current generated by VSG, an improved algorithm for obtaining inductance current reference value based on double second-order generalized integral is proposed. Inertial integral link is used to replace differential operation in full feed-forward control for grid voltage, and the mechanism of current regulator is analyzed. The current tracking and harmonic suppression can be realized by choosing the corresponding current regulator. Finally, a simulation and experimental platform is built to verify the validity of the improved VSG control strategy.