基于广义短路比的LCC/VSC混合多馈入系统小干扰稳定分析OA

The configuration of hybrid receiving-end power grids fed by both line commutated converter based high voltage direct current(LCC-HVDC)and voltage source converter based HVDC(VSC-HVDC)systems is emerging,and accurately quantifying the stability margin of hybrid multi-infeed systems is crucial.The short-circuit ratio is often used to describe voltage stability margins in traditional LCC-HVDC multi-infeed systems.However,in hybrid multi-infeed systems,the mechanism and definition of the short circuit ratio(SCR)remain unclear.To address this issue,this paper proposes a method for quantifying the stability margin of hybrid multi-infeed systems based on the generalized SCR(gSCR)from the perspective of small-signal stability.Firstly,a small-signal admittance model for LCC-HVDC is established,and the impact of the phase-locked loop on the small-signal stability of LCC-HVDC is investigated using the synchronous dominant loop method.Secondly,the maximum singular value of the impedance matrix of VSC-HVDC is utilized in characterizing the voltage support capability of VSC-HVDC in hybrid multi-infeed systems.Finally,the gSCR is extended to hybrid multi-infeed systems,and a quantitative assessment method for the small-signal stability margin of hybrid multi-infeed systems is proposed.Simulation examples verify the effectiveness of the proposed method.