Stepwise Parameter Identification Of Fault Ride-through Control Strategy Of PMSG Grid-connected Inverter

Renwable energy power source is connevted to the AC system through the power electronic converter.The characteristics of short-circuit current provided by the renewable energy sources are significantly different from the characteristics of short-circuit current provided by the synchronous machine,which may cause the sensitivity of traditional protection to decrease,or even the protection to refuse to move.Accurate simulation model and parameters close to the actual project are the basis for studing the fault characteristics and protection technology of renewable energy sources.However,most of the existing research objects of parameter identification focus on parameters of steady-state,which is lack of identification research on parameters of fault control strategy with different influence weights.Therefore,the identification research of parameters of fault control strategy of renewable energy sources based on external characteristic data is of great significance.This paper established the electromagnetic transient model of PMSG that meets the requirements of the national standard firstly.By configuring the FRT control strategy for GSC,MSC and the DC chopper circuit of PMSG with the actual project,make the model of PMSG meet the relevant requirements of the national standard.The characetristics of PMSG are analyzed when a fault occured on the PCC and the conclusion is drawn that the fault characteristics are mainly affected by the FRT control strategy of GSC.Secondly,the fault control parameters that have a direct impact on the fault characteristics of PMSG are screened.By deriving the FRT control transfer function of GSC,with the analysis result of the influence of PLL and delay link on the fault transfer function,the parameters to be identified are obtained by screening,which lays the foundation for the subsequent parameter identification research.Finally,a stepwise identification algorithm for FRT control parameters based accelerated PSO algorithm is proposed.According to FRT control transfer function of GSC,the sensitivity of the parameters to be identified is analysized and the identification priority is clarified.Therefore,a stepwise parameter identification algorithm based on accelerated PSO algorithm is proposed,which solved the problem that parameters with different sensitivities cannot be identified simultaneously.Relying on actual engineering parameters,modeling on PSCAD/EMTDC,using simulation data to verify the feasibility of the stepwise parameter identification method.