Title: Generalized Short Circuit Ratio for Multi Power Electronic based Devices Infeed Systems: Defi-nition and Theoretical Analysis,
Abstract: Short circuit ratio (SCR) is widely applied to analyze the strength of AC
system and the small signal stability for single power elec-tronic based
devices infeed systems (SPEISs). However, there still lacking the theory of
short circuit ratio applicable for multi power electronic based devices infeed
systems (MPEIS), as the complex coupling among multi power electronic devices
(PEDs) leads to difficulties in stability analysis. In this regard, this paper
firstly proposes a concept named generalized short circuit ratio (gSCR) to
measure the strength of connected AC grid in a multi-infeed system from the
small signal stability point of view. Generally, the gSCR is physically and
mathematically extended from conven-tional SCR by decomposing the multi-infeed
system into n inde-pendent single infeed systems. Then the operation gSCR
(OgSCR) is proposed based on gSCR in order to take the variation of op-eration
point into consideration. The participation factors and sensitivity are
analyzed as well. Finally, simulations are conducted to demonstrate the
rationality and effectiveness of the defined gSCR and OgSCR.