**8. Conclusions**

This paper has presented an effective PFCS based on the centralized control approach and a reliable DCV restoration algorithm for DCMG under grid fault conditions. The main contributions of this paper can be summarized as follows:

(i) By taking into account the relationship of supply-demand power and the statuses of system units such as the UG, WPGS, and battery, the CC generates thirteen proper operating modes to each LC to effectively deal with various conditions in DCMG. As a result, the stability of DCV and the system power balance can be guaranteed. Moreover, by considering both the grid-connected and islanded modes, a comprehensive performance evaluation for the PFCS was undertaken.


In order to evaluate the feasibility of the PFCS and the proposed DCV restoration algorithm, a prototype DCMG, consisting of three-phase grid-connected converter, WPGS, and lithium-ion battery-based ESS, was constructed by using 32-bit floating-point digital signal processor (DSP) TMS320F28335 controller. In the experimental setup, the wind turbine emulator consisting of a coupled PMSM-inductor machine and three-phase converter was employed for the WPGS. Comprehensive simulation and experimental results based on the PSIM and DCMG testbed are presented to verify the effectiveness of the PFCS and the proposed DCV restoration algorithm.

**Author Contributions:** T.V.N. and K.-H.K. conceived the main concept of the control structure and developed the entire system. T.V.N. carried out the research and analyzed the numerical data with guidance from K.-H.K. T.V.N. and K.-H.K. collaborated in the preparation of the manuscript.

**Funding:** "This research was funded by Seoul Tech (Seoul National University of Science and Technology)" and "The APC was funded by Seoul Tech (Seoul National University of Science and Technology)".

**Acknowledgments:** This study was supported by the Advanced Research Project funded by the SeoulTech (Seoul National University of Science and Technology).

**Conflicts of Interest:** The authors declare no conflict of interest.
