Exploiting Redundant Energy of MMC-HVDC to Enhance Frequency Response of Low Inertia AC Grid

Heejin Kim, Jaesik Kang, Jae W. Shim, Jef Beerten, Dirk Van Hertem, Hong Ju Jung, Chan Ki Kim, Kyeon Hur

Research output: Contribution to journalArticlepeer-review

13 Citations (Scopus)


This paper presents a grid frequency responsive inertial control for the modular multilevel converter-high voltage DC (MMC-HVDC) using the MMC design attribute, i.e. submodule redundancy for high reliability. This control does not rely on the external energy sources in providing the inertial response. With an increase in the number of levels of MMCs via the proposed ${n}_{level}$ control, the submodule capacitor voltage decreases, and the electrostatic energy then flows from the submodule capacitors and supports extra power to the grid in need. Decoupled control of the AC, DC and submodule dynamics of the MMC maintains the desired control performance during and after the inertial response, emulating the inherent behavior of the synchronous machine. This study further quantifies the inertia constant of the MMC, equivalent to that of the synchronous machine. The proposed control performance is demonstrated in the context of a Jeju Island power grid with MMC-HVDC systems for the offshore wind interconnection and interconnection between mainland and Jeju. Simulation results present that the proposed method improves the frequency response in harmony with existing synchronous generators and line-commuted converter based HVDC system.

Original languageEnglish
Article number8846030
Pages (from-to)138485-138494
Number of pages10
JournalIEEE Access
Publication statusPublished - 2019

Bibliographical note

Funding Information:
This work was supported in part by under the framework of international cooperation program managed by the National Research Foundation of Korea under Grant 2017K1A4A3013579, and in part by the Basic Science Research Program through the National Research Foundation of Korea funded by the Ministry of Education, Science and Technology under Grant 2018R1D1A1A09083054.

Publisher Copyright:
© 2013 IEEE.

All Science Journal Classification (ASJC) codes

  • Computer Science(all)
  • Materials Science(all)
  • Engineering(all)


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