Journal of Modern Power Systems and Clean Energy

ISSN 2196-5625 CN 32-1884/TK

Joint Limiting Control Strategy Based on Virtual Impedance Shaping for Suppressing DC Fault Current and Arm Current in MMC-HVDC Systems
Author:
Affiliation:

1.College of Electrical Engineering, Sichuan University, Chengdu 610065, China
2.Smart Grid Key Laboratory of Sichuan Province, Chengdu 610065, China
3.State Grid Jiangsu Electric Power Company Research Institute, Nanjing 211103, China
4.Department of Energy Technology, Aalborg University, Aalborg 9920, Denmark
5.School of Electrical and Electronic Engineering, Nanyang Technological University, Singapore 639798, Singapore

Fund Project:

This work was supported in part by the Fundamental Research Funds for the Central Universities (No. 2022SCU12005) and the General Project of Natural Science Foundation of Sichuan Province (No. 2022NSFSC0262).

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    Abstract:

    This paper proposes a joint limiting control strategy for suppressing DC fault current and arm current in modular multilevel converter-based high-voltage direct current (MMC-HVDC) systems, which includes two target-oriented current limiting controls. To limit the DC fault current in the early fault stage, an equivalent modular multilevel converter (MMC) impedance is obtained, and its high-frequency part is reshaped by introducing virtual impedance, which is realized by adjusting the inserted submodules adaptively. Following the analysis of MMC control characteristics, the arm current limiting strategy is investigated, with results showing that the inner-loop control has significant effects on arm current and that a simple low-pass filter can reduce the arm current in the fault period. Finally, by combining the virtual impedance shaping and inner-loop control, the fault currents of DC lines and MMC arms can be suppressed simultaneously, which can not only alleviate the interrupting pressure of the DC circuit breaker, but also prevent the MMC from being blocked by the arm overcurrent. Theoretical analysis conclusions and the proposed strategy are verified offline by a digital time-domain simulation on Power Systems Computer Aided Design/Electromagnetic Transients including DC platform, and experiment on a real-time digital simulator platform.

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History
  • Received:September 06,2022
  • Revised:December 20,2022
  • Adopted:
  • Online: November 16,2023
  • Published: