Equivalent Modeling Of Doubly-fed Wind Farm Based On DIgSILENT Software

With the development of renewable energy such as wind power,the proportion of wind power in the power grid is getting higher and higher,especially the intermittent and uncertain problems of wind energy,which makes the impact of high permeability wind power access on the power grid more and more serious.The large wind farms have a large number of generating units,and the DFIG is the mainstream type.The detailed wind model of doubly-fed wind farm is complex,the simulation efficiency is low,and the fault characteristics of doubly-fed wind turbine are complex.Therefore,the equivalent modeling of doubly-fed wind farm is very important to study the interaction between large-scale wind farm and power grid.Firstly,based on the basic structure of doubly-fed wind turbine,this paper studies the control strategy of wind speed model,wind turbine model,generator model,rotor-side and grid-side converter,and the function modules of each model in DIgSILENT software.The external characteristics of single-generator doubly-fed wind turbine under normal and fault conditions are simulated and studied.According to the voltage equation and flux linkage equation of doubly-fed wind turbine and the control of rotor-side converter,the fault transient characteristics of a single doubly-fed wind turbine are studied.A two-machine method based on the Crowbar operation state is proposed,and the critical operation of the Crowbar protection circuit based on the terminal voltage,wind speed and initial operation state of the wind turbine is given.Make a criterion.Aiming at the parameter equivalence method of doubly-fed wind farm,this paper presents the parameter equivalence method of unit and collector system based on capacity weighting method.Finally,the detailed model of doubly-fed wind farm is built in DIgSILENT simulation software,and the cluster division and dual-machine equivalent simulation of doubly-fed wind farm are realized by using the proposed method.The electrical waveforms of the equivalent model and the detailed model are compared,and the error analysis is carried out to verify the effectiveness of the proposed equivalent method.