Reseach Of Current Source Wind Power Converter Based On RB-IGBT

Due to extensive use of fossil fuels,Energy shortage and environment pollution have become an important issue faced by people.As a renewable and clean energy,wind power has been fully developed and utilized in the world.With the development of wind power technology,wind power generation system with high reliability and low maintenance cost extract more and more attentions and researches.Because of less power switches and no DC-link capacitor,CSC has higher reliability.But because of the limit of power switches,its cost and volume don't account for the advantages,comparing with the same-power-level VSC.Appearance of RB-IGBT gives CSC probilities to apply in the wind power converter.Therefore,this paper proposes the use of current source converter as the power converter for PMSG based direct-driven wind power generation system.Related researched in terms of control scheme of generator-side and grid-side converter,DC current optimizing control strategy and LC resonance suppression are carried out to meet the proposed configuration for wind turbine system,which can be concluded as following:(1)Structure of PMSG based current source wind power generation system and working principle of each part are introduced,and building mathematical model,including wind turbine,PMSG,current source converter in abc coordinates and dq coordinates.(2)The corresponding control strategy is designed based on different control target of each part of structure in PMSG based current source wind power system.For the wind turbine control target of maximum wind power capture,three kinds of control strategy under different wind speed are introduced,and compare the merits and demerits of above three kinds of control strategy;According to the control targets of generator-side and grid-side converter,generator-side control strategy based on rotor flux oriented and grid-side control strategy based on grid voltage oriented are designed;According to the characteristics of DC current can be affected by wind speed,to reduce the loss of the system,the minimum DC current expressions which meet controlling demands of generator-side and grid-side converter respectively is built,and analysis minimum DC current boundary conditions when converter can be operated normally.At last,simulation results validate the basic control algorithm.(3)Due to the existing of LC filter,converter may face the risk of resonance.A new active damping control strategy based on inductor current feedback is introduced based on analysis LC resonance mechanism.Then a detailed analysis of effect on active damping control imposed by grid inductance and modified active damping control strategy are given.In order to improve system reliability,a kind of grid current observer based virtual flux and CSR mathematical model is designed to realize active damping control without AC current sensor.At last,simulation results validate grid current observer and active damping control algorithm.(4)Various SVPWM modulation methods for current source converter are detailedly studied on the basis of theoretical analysis.For the quantitative analysis of RB-IGBT based current source wind power converter,a general analysis method of current source converter loss is introduced and the system switching loss model and conduction loss model under different modulation algorithm are established.Taking RB-IGBT based current source converter as an example,this paper analyzes current source wind power converter loss under different conditions and current source wind power converter loss during the whole life cycle.At last,a comparison with voltage source converter loss under same condition is made.