A self-adaptive control strategy of virtual inertia and a damping coefficient for bidirectional DC-DC converters in a DC microgrid

In a DC microgrid system with high penetration of new energy, the proportion of power electronic devices continues to increase. This leads to the problem of low inertia in the system and reduces the stability of the system. Therefore, an improved adaptive control strategy of virtual inertia and a damping coefficient is proposed. This method analyzes the relationship between load disturbance and output voltage disturbance in the DC microgrid system under the control of virtual inertia and damping coefficient by analogy to the virtual DC generator control of the inverter of the AC system, and introduces an adaptive control strategy into virtual inertia and the damping coefficient. By establishing a small signal model, using the system output impedance combined with the impedance ratio criterion, the range and boundary of the virtual inertia and damping coefficient are given, and the effect of system inertia change and bus voltage response under the adaptive selection of virtual inertia and damping coefficient is analyzed. The strategy increases the inertia of the DC microgrid system and improves the dynamic response of the DC bus. Finally, Matlab/Simulink simulation and RT-LAB hardware in a loop experiment verify the effectiveness of the proposed control strategy. © 2022 Power System Protection and Control Press.