TY - JOUR
T1 - An Improved Synchronization Stability Method of Virtual Synchronous Generators Based on Frequency Feedforward on Reactive Power Control Loop
AU - Xiong, Xiaoling
AU - Wu, Chao
AU - Blaabjerg, Frede
PY - 2021
Y1 - 2021
N2 - The synchronization stability of the virtual synchronous generator (VSG) under grid fault is an important issue for maintaining stable operation in the power system. Existing work has pointed out a low-pass filter (LPF) with a sufficiently low cutoff frequency in the reactive power control loop (RPCL) can improve the transient stability. Yet, the underlying mechanism was unknown. Moreover, as a key index of VSG and precondition of synchronization stability, the frequency response is rarely studied. In this article, based on the linearized model for qualitative analysis, combined with the nonlinear model for quantitative analysis, the underlying mechanism of improving synchronization stability using an LPF in the RPCL is revealed. Furthermore, to avoid increasing the system order and solve the conflict between transient stability and frequency response, an improved synchronization stability method is proposed by feedforwarding the frequency difference between the VSG and grid to the RPCL. The frequency response is also acquired based on the combined linearized and nonlinear model, which shows that the frequency feedforward method can further enhance the frequency stability. How to design the coefficient of the frequency feedforward path with different inertia requirements is also presented. Finally, this method is verified by experimental results.
AB - The synchronization stability of the virtual synchronous generator (VSG) under grid fault is an important issue for maintaining stable operation in the power system. Existing work has pointed out a low-pass filter (LPF) with a sufficiently low cutoff frequency in the reactive power control loop (RPCL) can improve the transient stability. Yet, the underlying mechanism was unknown. Moreover, as a key index of VSG and precondition of synchronization stability, the frequency response is rarely studied. In this article, based on the linearized model for qualitative analysis, combined with the nonlinear model for quantitative analysis, the underlying mechanism of improving synchronization stability using an LPF in the RPCL is revealed. Furthermore, to avoid increasing the system order and solve the conflict between transient stability and frequency response, an improved synchronization stability method is proposed by feedforwarding the frequency difference between the VSG and grid to the RPCL. The frequency response is also acquired based on the combined linearized and nonlinear model, which shows that the frequency feedforward method can further enhance the frequency stability. How to design the coefficient of the frequency feedforward path with different inertia requirements is also presented. Finally, this method is verified by experimental results.
KW - Frequency stability
KW - reactive power control loop
KW - synchronization stability
KW - virtual inertia
KW - virtual synchronous generators (VSGs)
UR - http://www.scopus.com/inward/record.url?scp=85099731418&partnerID=8YFLogxK
U2 - 10.1109/TPEL.2021.3052350
DO - 10.1109/TPEL.2021.3052350
M3 - Journal article
SN - 0885-8993
VL - 36
SP - 9136
EP - 9148
JO - IEEE Transactions on Power Electronics
JF - IEEE Transactions on Power Electronics
IS - 8
M1 - 9328607
ER -