Small-Signal Stability of Grid-Forming Converters Under Fault Conditions

Yin Chen, Xianxian Zhao, Qianchao Liao, Yinyu Chen, Xia Chen, Lie Xu

Research output: Chapter in Book/Report/Conference proceedingConference contribution book

Abstract

The threshold virtual impedance (TVI) method is gaining significant research interest for limiting current in grid-forming (GFM) converters under fault conditions. This method is valued for its ability to maintain voltage source behavior during such faults. However, sequence extraction and negative-sequence control (NSC) are often overlooked in small-signal stability assessments under these conditions. This paper develops a small-signal impedance model for GFM converters based on the TVI current limitation method during fault conditions. Using developed small-signal impedance model, the impact of NSC on system stability during faults is analyzed. Additionally, key TVI parameters, such as the low-pass filter (LPF) cutoff frequency and the impedance ratio X/R are examined. The findings suggest that NSC, a lower LPF cutoff frequency, and a lower X/R ratio enhance system stability under fault conditions. However, a lower cutoff frequency may not effectively limit fault currents, and a lower X/R ratio can lead to reduced voltage magnitude during faults. Time-domain simulations validate these analytical results.
Original languageEnglish
Title of host publication2024 IEEE 7th Student Conference on Electric Machines and Systems (SCEMS)
PublisherIEEE
Pages1-6
Number of pages6
ISBN (Electronic)979-8-3503-6694-5
ISBN (Print)979-8-3503-6695-2
DOIs
Publication statusPublished - 25 Nov 2024
Event2024 IEEE 7th Student Conference on Electric Machines and Systems (SCEMS) - Macao, Macao
Duration: 6 Nov 20248 Nov 2024

Publication series

Name2024 IEEE 7th Student Conference on Electric Machines and Systems (SCEMS)
PublisherIEEE
ISSN (Print)2771-7550
ISSN (Electronic)2771-7577

Conference

Conference2024 IEEE 7th Student Conference on Electric Machines and Systems (SCEMS)
Country/TerritoryMacao
CityMacao
Period6/11/248/11/24

Keywords

  • Grid-forming converter
  • virtual impedance
  • fault
  • negative-sequence control
  • small-signal stability

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