In dc microgrids (dc MGs), the dc link capacitor is very small to provide the inherent inertial. As a result, large voltage deviations occur during load changes or uncertain fluctuations from the fluctuated power resources. This leads to degradation of voltage quality. To overcome the low inertia problem, this paper proposes a fast-responding energy storage system such as supercapacitor can mimic inertial responses through some specified control algorithm. A bidirectional dc–dc converter is used for interfacing supercapacitor energy storage to a dc MG. The proposed control scheme is composed of a virtual capacitor and a virtual conductance. It is implemented in the inner loop controls, i.e. current loop control to be fast enough emulating inertia and damping concept. In order to study the stability of dc MG, a comprehensive small-signal model is derived and then, an acceptable range of inertia response parameters is determined by using the system's root locus analysis. Performance of the proposed control structure is demonstrated through numerical simulations.

在直流微电网（dc MG）中，直流链路电容器非常小，可以提供固有的惯性。结果，在负载变化期间或由于波动的电源引起不确定的波动时，会出现较大的电压偏差。这导致电压质量下降。为了克服低惯性问题，本文提出了一种快速响应的能量存储系统，例如超级电容器可以通过某些指定的控制算法来模拟惯性响应。双向dc-dc转换器用于将超级电容器能量存储与dc MG接口。所提出的控制方案由虚拟电容器和虚拟电导组成。它在内部回路控制中实现，即电流回路控制足够快地模拟惯性和阻尼概念。为了研究直流MG的稳定性，推导了一个综合的小信号模型，然后使用系统的根轨迹分析确定了可接受的惯性响应参数范围。通过数值仿真证明了所提出的控制结构的性能。