TY - GEN
T1 - Small-Signal Stability of Grid-Forming Converters Under Fault Conditions
AU - Chen, Yin
AU - Zhao, Xianxian
AU - Liao, Qianchao
AU - Chen, Yinyu
AU - Chen, Xia
AU - Xu, Lie
PY - 2024/11/25
Y1 - 2024/11/25
N2 - 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.
AB - 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.
KW - Grid-forming converter
KW - virtual impedance
KW - fault
KW - negative-sequence control
KW - small-signal stability
U2 - 10.1109/scems63294.2024.10756384
DO - 10.1109/scems63294.2024.10756384
M3 - Conference contribution book
SN - 979-8-3503-6695-2
T3 - 2024 IEEE 7th Student Conference on Electric Machines and Systems (SCEMS)
SP - 1
EP - 6
BT - 2024 IEEE 7th Student Conference on Electric Machines and Systems (SCEMS)
PB - IEEE
T2 - 2024 IEEE 7th Student Conference on Electric Machines and Systems (SCEMS)
Y2 - 6 November 2024 through 8 November 2024
ER -