**5. Conclusions**

This paper proposes a modified compensation method for the MW-scaled AC–DC hybrid systems such as storage devices. To perform the ESS operation with an effective reference order, a voltage-estimation method was formulated and adopted in the designed generation system. Verification of the performance improvement in regard to the real power managemen<sup>t</sup> that responds

to the order is verified through case studies. According to the changed state in terms of load, the proposed controller generated a precise order considering the real power extraction from the DC network. The MW-scaled DC networks with different sources experience voltage fluctuation when interworking with the grid. In case of the proposed method, however, it is required to establish the power production of the module as an input signal since credibility is required not only on the PV module but also on the applied sensors. When pursuing detailed managemen<sup>t</sup> of large-scale DC systems, the application could be considered by the ESS operator. In general, the large-scale DC networks with diverse sources have voltage fluctuation when interworking with the grid. The designed method is based on a multiple PV system, the active support plan using ESS is able to further expand large DC system. Even if the error mitigation on the basis of the order is a minor issue in certain system, the improvement can be useful for the ESS managemen<sup>t</sup> process with respect to state of charge. The controller will improve estimation accuracy of the remaining amount for the ESS, and this can help support operational accuracy.

**Author Contributions:** Conceptualization, Y.Y. and S.J.; Methodology, S.J.; Software, Y.Y.; Validation, Y.Y., and S.J.; Formal Analysis, J.-H.K., I.N. and M.Y.; Investigation, J.-H.K., I.N. and M.Y.; Data Curation, J.-H.K., I.N. and M.Y.; Writing-Original Draft Preparation, S.J.; Writing-Review and Editing, S.J. and G.J.; Supervision, S.J.; Project Administration, S.J. and G.J.; Funding Acquisition, S.J.

**Funding:** This work was supported by the National Research Foundation Grant (No. 2018R1C1B5030524) and the Korea Institute of Energy Technology Evaluation and Planning/MOTIE (No. 20184030201900) funded by the Korean government.

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