Voltage of DC microgrid is prone to oscillation, originated from the following three factors: 1) negative damping performance of the DC converter; 2) interaction between the power converter and DC network; and 3) positive feedback (PF) of DC voltage control loop. Analogous to the relationship between the force and velocity of motion, it derives the functional relationship between DC current and DC voltage. The motion of DC voltage can be illustrated by the derived vectors since transfer functions between DC current and DC voltage have the corresponding phase and gain at a specific frequency. It is found that it forms a PF when the damping of the DC converter is negative, which can destabilize DC-side voltage at the oscillated frequency. However, a negative feedback can stabilize the system and make the DC voltage attenuated. A virtual inertia (VI) control strategy is proposed for the enhancement of damping performance and forming a negative feedback for the system. The proposed theoretical analysis is demonstrated by Star-Sim hardware-in-the-loop (HIL) experiments.

中文翻译：

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具有负反馈效应的改善直流微电网阻尼性能的虚拟惯性控制策略

直流微电网的电压容易产生振荡，其原因有以下三个：1）直流变换器的负阻尼性能；2）电源转换器与直流网络之间的相互作用；3）直流电压控制回路的正反馈（PF）。类似于力和运动速度之间的关系，它推导了直流电流和直流电压之间的函数关系。直流电压的运动可以用导出的矢量来说明，因为直流电流和直流电压之间的传递函数在特定频率下具有相应的相位和增益。已经发现，当直流转换器的阻尼为负时，它会形成PF，这可能会使振荡频率下的直流侧电压不稳定。但是，负反馈可以使系统稳定，并使直流电压衰减。提出了一种虚拟惯性（VI）控制策略，以增强阻尼性能并为系统形成负反馈。Star-Sim硬件在环（HIL）实验证明了所提出的理论分析。