Connecting converter-based renewable power generators (RPGs) to the power grid can cause serious sub-/super-synchronous oscillations (SSO).Changes in the operating conditions,grid strengths,and converter control can cause the SSO frequency to gradually approach the fundamental frequency while then leads to low-frequency small-signal synchronizing stability (SSS) oscillations.This paper compares the characteristics of SSO and SSS oscillations using the impedance model (IM)-based method that has been used to analyze SSO and is believed to be useful for analyzing the low-frequency oscillations caused by synchronous instabilities.Then,a mathematical model is used to show the equivalence between the phase-locked loop (PLL) dynamic equation-based method and the IM based method for the same grid-tied voltage source converter (VSC) system as a theoretical foundation for SSS analyses using the IM-based method.Finally,time-domain simulations verify the accuracy of the IM-based method for analyzing SSS oscillations of converter-based RPGs.
LIU Wei
,
XIE Xiaorong
,
JIANG Qirong
,
MAO Hangyin
. Sub-/super-synchronous oscillation,small signal synchronizing stability,and impedance model analysis of converter-based renewable power generators[J]. Journal of Tsinghua University(Science and Technology), 2022
, 62(10)
: 1706
-1714
.
DOI: 10.16511/j.cnki.qhdxxb.2022.21.004
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