**6. Conclusions**

This study has proposed a new control scheme regarding distributed LVRTC and real-time reactive power compensation functions for the operation of WTGs in a wind farm according to E.ON's specifications. The proposed compensation scheme using distributed LVRTCs can effectively enhance reliability, as well as reduce cost compared with centralized LVRT compensators. In addition, with the help of the proposed LVRTC scheme, WTGs can continuously output real power within their maximum current limit during the period of voltage drop, which is a great merit for the secure operation of modern power distribution systems embedded with WTGs. In this study, a complete design example of LVRTCs using silicon carbide (SiC), a wide band gap (WBG) semiconductor, based three-phase voltage source inverter has been demonstrated. The mathematical models of inverter systems have been derived using the dq-axis decoupling method to enable separate control of active and reactive powers. On the basis of the results obtained from the simulation and hardware tests, when a voltage fault occurs, the proposed control scheme can achieve a good regulation of LVRTCs' DC bus voltage, and the real-time compensation of appropriate reactive current according to the grid code to help restore the nominal grid voltage.

**Author Contributions:** The corresponding author, C.-T.M., conducted the research work, verified the results of the simulation cases and hardware tests, wrote the draft, and polished the final manuscript. Z.-H.S., a student who graduated from the department of EE, CEECS, National United University, Taiwan, assisted in paper searching and organized the test results. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research was funded by MOST, Taiwan, with grant number MOST 110-2221-E-239-032.

**Institutional Review Board Statement:** Not applicable.

**Informed Consent Statement:** Not applicable.

**Data Availability Statement:** No new data were created or analyzed in this study. Data sharing is not applicable to this article.

**Acknowledgments:** The author would like to thank the Ministry of Science and Technology (MOST) of Taiwan for financially supporting the energy-related research regarding key technologies in microgrids, and the design of advanced power and energy systems.

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