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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 article, 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 the 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 similar as the oscillation frequency and fluctuation ranges of poorly-damped oscillation, respectively. A unified concept is proposed by connecting the oscillation-related stability with the inertial transient response originated from the imbalanced powers/mismatched currents. Besides 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. [ABSTRACT FROM AUTHOR]

Virtual synchronous generator (VSG), recognized as a grid-friendly control technique, contributes to providing inertia and damping support from the grid-tied power electronic systems. However, similar to the conventional synchronous generator, the VSG is vulnerable to wideband oscillations and can even become unstable when the system is subjected to a variety of disturbances. To tackle this issue, this article proposes a magnitude-phase motion equation (MPME) for grid-forming VSG attached to a weak grid. Besides, a feedback analytical method is introduced to identify the frequency dynamic stability, judged by the sign of (dω/dt)/δω. Besides, the rate of change of frequency (RoCoF) and frequency nadir (FN) are evaluated by the two indices, i.e., dω/dt and δω. In addition, the relationship between the low-inertia-RoCoF-FN-related stability and the weak-damping-oscillation-related stability is illustrated by the feedback analysis. Moreover, in the framework of MPME, a reactive-power feedforward (RPFF) decoupling control strategy is proposed for the enhancement of stability and robustness performance of the VSG system. Finally, the proposed modeling and the RPFF decoupling control strategy are demonstrated with the experiments. [ABSTRACT FROM AUTHOR]

• This article proposes virtual inertia and virtual damping based output impedance amplitude compensation control strategy to dampen oscillation of DC-side voltage. • The proposed virtual inertia control provide a amplitude compensation of output impedance, and damping the fluctuation of DC voltage caused by interaction between DC converter and the remaining networks of the DC microgrid. Voltage is prone to oscillation in a DC microgrid because of interaction between the power converter and the remaining parts of the networks. For this issue, this paper develops an impedance modeling based on linearization method for stability analysis. It is found that the wideband oscillation is prone to occurring concluded from stability analysis. Furthermore, the impact of parameters on stability of the microgrid is studied. Besides, a new closed-loop control model is proposed based on the DC current control loop. It is found that the current loop includes a peak which may impact the voltage oscillations. It is because voltages are interacted with the currents. Based on this idea, a new amplitude compensation control strategy based on virtual inertia emulation is proposed to dampen oscillation of the voltages by shaping the amplitude of output impedance. And theoretical analysis show good feasibility of the proposed control. Finally, the proposed conceives are demonstrated by experiments. [ABSTRACT FROM AUTHOR]

• This article proposes a VSM control strategy to dampen oscillation of DC-side voltage, and to improve damping performance and inertia for DC power system. • This paper proposed a new modeling method for identifying the dynamic interactions between multiple converters in a DC microgrid. DC system is characterized by low inertia and weak damping, which leads to a couple of stability issues. This paper proposes a modeling method for analyzing the DC-side oscillations occurred in DC microgrid with taking multi-paralleled converters into account. A new modeling is developed for analysis of dynamic interaction between multiple power converters. Thus, it is found that dynamic interaction between multiple converters will result in the poorly-damped oscillation of DC voltage. Besides, the poorly-damped modes will aggravate the stability of DC system. To cope with this issue, a virtual synchronous machine (VSM) control approach is proposed to suppress the oscillation of DC voltage, strengthen inertia, and improve damping performance of DC microgrid. Besides, the controller tuning of the VSM has a large flexibility that it does not depend on the system parameters. Finally, the proposed conceives are demonstrated by simulations. [ABSTRACT FROM AUTHOR]

• This article proposes a VSG CONTROL method to dampen oscillation of DC voltage, improve damping performance as well as inertia. • This paper analyzed the mechanism of VSG damping oscillation and improving damping performance of DC voltage in the framework of impedance modeling. DC-side oscillation problems trouble the stable and secure operation of voltage source converter high voltage direct current (VSC-HVDC) systems. Therefore, it is of considerable significance to investigate the physical origins of these oscillations. Thus, this paper proposes an impedance-based method for VSC-HVDC system DC stability analysis. Differently, a new perspective for DC resonance interaction is introduced, which is judged by the interactive behavior of two subsystems impedances, namely converter impedance and DC network impedance. Also, the proposed method quantitatively estimates the damping of DC schemes of VSC-HVDC system. Based on the proposed method, it is found that the global stability of VSC-HVDC system can be guaranteed if and only if: 1) subsystems are passive and locally stable, 2) there is no resonance interaction between inductive impedance and capacitive impedance, and 3) damping of DC system is large enough. Moreover, another contribution is to apply the virtual synchronous generator (VSG) control technique in VSC-HVDC system to dampen DC-side oscillation caused by impedance interaction. Specifically, this VSG control enhances inertia and damping of VSC-HVDC system on DC-side. Finally, the feasibility of the proposed technique and the accuracy of the mathematical model are demonstrated through simulation and experimental results. [ABSTRACT FROM AUTHOR]