Design And Algorithm Modulation Of T-type Three-level Power Conversion Converter

The development of the whole human society is now facing with two serious problems:the gradual exhaustion of fossil energy and the increasingly serious ecological crisis.The key to solving these two problems is to vigorously develop clean energy.At present,wind power,photovoltaic and other new energy power generation have been widely used,but this kind of clean energy power generation is limited by the external environment.Besides,the large fluctuation of electric energy lead to unstable and unsustainable.On the other hand,the application of energy storage on the new energy side can greatly solve the fluctuation of wind and solar energy to a certain extent,reduce wind and solar abandonment,and meet the increasing demand for grid regulation.Therefore,the use of energy conversion system on the power generation side will greatly increase the scale and application of new energy grid-connected power generation.Power Conversion System-PCS,as the link of energy conversion between battery and Power grid,is the core part of energy storage system.In this paper,the T-type three-level AC/DC energy storage converter has been deeply studied,mainly including the following contents:（1）The topological structure and working principles of the T-type three-level circuit are discussed,and the mathematical model of two-way power conversion of the converter is deduced and established.At the same time,the LCL filter is designed on the AC side according to the harmonic characteristics of the converter.（2）The modulation strategy of three-level SVPWM is studied,and an algebraic judgment tool to optimize the judgment method of small sector is proposed.The simulation results show that PCS has good bidirectional power conversion function and dynamic response characteristics.（3）At present,the construction of PCS experimental platform requires expensive space cost and maintenance cost.In order to solve this problem,this paper proposes a new test method for PCS test,and builds the corresponding test method model simulation.The simulation analysis shows that this test method can verify the function and effect of energy storage converter to some extent.（4）Design and build a 630 kW PCS prototype,which includes structure design,power supply circuit design,analog data acquisition module design,I/O module design,PWM output circuit design,IGBT drive circuit design.The correctness of the principle and the validity of the structure design are verified by the analysis of the experimental results of the prototype.