Secondary frequency modulation control and stability analysis of AC microgrid based on virtual synchronous generator characteristics

In this chapter the AC microgrid based on virtual synchronous generator (VSG) control is introduced. Firstly the control technology is introduced briefly. Then the feedback quantity of the inner loop in the droop control system is designed by using the transfer function and frequency domain diagram. Secondly the second-order transient mathematical model is selected to design the power frequency controller and excitation regulator of VSG. Considering that the traditional droop control only satisfies the primary frequency regulation, this chapter introduces the method of realizing the frequency tracking without difference by forming the secondary frequency modulation through the integrator to improve the power sharing accuracy and the power frequency characteristics of the AC microgrid. Finally, by establishing the model of AC microgrid based on VSG, the control system designed in this chapter is verified. The simulation results show that the control system of the microgrid has good active and reactive power sharing performance and provides inertia and damping for the system, which improves the power supply quality and stability of the microgrid.