Research On PMSG Wind Farm Equivalent Modeling Based On Low Voltage Ride Through Control

With the rapid development of wind power technology,the installed capacity of wind farms continues to increase,and the impact of large-scale wind farms on the safety and stability of power system is increasingly significant.It is necessary to establish an equivalent model to simplify the calculation.In order to provide an effective model basis for online simulation analysis of wind farms,it is urgent to establish a reasonable and effective wind farm equivalent model.Based on the low voltage ride through control strategy of PMSG,this paper proposes an equivalent modeling method suitable for largescale PMSG wind farms.The main work content and research results are as follows:Firstly,based on the analysis of the working principle and control characteristics of PMSG,the electromagnetic transient mathematical model is established and the control strategies of the machine-side converter and the grid-side converter are mainly studied,which paves the way for the equivalent modeling of the PMSG wind farm.Secondly,in order to improve the accuracy and stability of traditional K-means clustering algorithm,an improved algorithm combining density clustering and partitioning clustering is proposed.The simulation result shows that the D-K clustering algorithm has good adaptability in wind farm equivalent modeling.Thirdly,the LVRT implementation method of PMSG during grid fault is studied.Taking this as a starting point,an offline transient equivalent modeling method suitable for PMSG wind farms is proposed.Group the wind fram according to the conduction condition of the chopper circuit for the first time.The terminal voltage of the unconducted PMSG during the fault is taken as the cluster index,and the improved D-K clustering algorithm is used to group for the second time.Finally,in order to improve the timeliness and accuracy of the wind farm equivalent model,an online dynamic equivalent modeling method is proposed based on offline method.The method is based on the idea of establishing an offline equivalent model database and matching the best reference conditions online.Through the study simulation,the accuracy of the offline equivalent model and the online equivalent model under continuous fault conditions are compared and analyzed,which verifies the rationality of the online dynamic equivalent modeling method.