A New Secondary Frequency Control Method for Distributed VSGs in Island Operation

Virtual synchronous generator (VSG) control technology is widely used in off-grid control of distributed power supply by simulating the characteristics of synchronous generator, increasing the inertia of the system, realizing the advantages of frequency regulation and voltage regulation. In the multi-VSGs islanded operating system, the damping function of VSG can play a role of primary frequency modulation similar to droop control. The load increment is distributed according to the damping coefficient. When the system frequency crosses the line due to sudden load change, the droop characteristic can be changed to bring the system’s frequency back to the normal range. The secondary frequency modulation characteristics of translation droop curve method and changing damping coefficient method are analyzed, and a joint adjustment method combining translation droop curve and changing damping coefficient is proposed. Finally, simulation experiments are carried out on Matlab/Simulink platform to verify the effectiveness of the proposed method.