跟网型与构网型变流器并存电力系统的混合频域建模与稳定性分析

With the increase of the renewable energy genera-tor capacity,the requirements of the power system for grid-con-nected converters are evolving,which leads to diverse control schemes and increased complexity of systematic stability analy-sis.Although various frequency-domain models are developed to identify oscillation causes,the discrepancies between them are rarely studied.This study aims to clarify these discrepan-cies and provide circuit insights for stability analysis by using different frequency-domain models.This study emphasizes the limitations of assuming that the transfer function of the self-sta-ble converter does not have right half-plane(RHP)poles.To en-sure that the self-stable converters are represented by a fre-quency-domain model without RHP poles,the applicability of this model of grid-following(GFL)and grid-forming(GFM)converters is discussed.This study recommends that the GFM converters with ideal sources should be represented in parallel with the P/Q-θ/V admittance model rather than the V-I imped-ance model.Two cases are conducted to illustrate the rationali-ty of the P/Q-θ/V admittance model.Additionally,a hybrid fre-quency-domain modeling framework and stability criteria are proposed for the power system with several GFL and GFM con-verters.The stability criteria eliminates the need to check the RHP pole numbers in the non-passive subsystem when applying the Nyquist stability criterion,thereby reducing the complexity of stability analysis.Simulations are carried out to validate the correctness of the frequency-domain model and the stability cri-teria.