Virtual synchronous generator (VSG) has been a grid-friendly integration control technique for the integration of grid-connected inverters. However, the emulated inertia and damping of VSG control technique can also be used in the field of DC systems. In this paper, a virtual synchronous control is proposed to dampen the wideband oscillation of DC voltage in a DC microgrid. The proposed control strategy contributes to maintaining synchronous operation of DC converter with the network. Besides, the relationships among damping, inertia, wideband oscillation, rate of change of voltage (RoCoV) as well as DC voltage nadir (DCVN) are studied. It is concluded that the RoCoV and DCVN are similarly as the oscillation frequency and fluctuation ranges of poorly-damped oscillation, respectively. A unified concept is proposed by connecting the oscillation-related stability with inertial transient response originated from the imbalanced powers/mismatched currents. Besides of this, the inertia plays the same role as damping because the inertia contributes to maintaining the original state and damping to impeding further change. A new feedback analytical method is proposed to clarify the important role of RoCoV and DCVN on the motion of DC voltage. Finally, the theoretical results are compared with simulations and experiments.
- DC voltage nadir (DCVN)
- Feedback analytical method
- Inertia and damping
- Poorly-damped oscillations
- Rate of change of voltage (RoCoV)
- Virtual synchronous generator (VSG)
- Voltage control