Research On Unified Power Flow Controller Based On Multi-level Technology

As the global energy Internet gradually and the rapid development of market economy,the demand for electricity is growing,the existing power system transmission capability of insufficient contradiction is also growing,and build new transmission lines under land,the environment,restrictions of many objective factors,such as cost and difficult to implement.As a result,the flexible alternating current transmission system(FACTS)was born and became more and more popular.Unified power flow controller(UPFC)as the most representative in the family of flexible alternating current transmission system,the most powerful comprehensive compensation device is becoming a hot spot of research.Based on the analysis of topological structure,work principle and mathematical model of UPFC,respectively based on three-level converter device of UPFC(TNPC-UPFC),based on the structure of the MMC UPFC(MMC-UPFC)both with multilevel technique of UPFC for detailed research and analysis.The main work is as follows:1)Power flow control in power grid are introduced the basic concept and basic method,then expounds in detail the overall topology of UPFC,introduces the mathematical model and control strategy of UPFC,before giving the mathematical model of UPFC also briefly introduces the coordinate transformation theory and the theory of pq,the two theories is the basis of the study of the mathematical model and control strategy of UPFC,and then analyze the power PLL,and gives the simulation model,and then a dynamic mathematical model of UPFC,and then gives the corresponding control strategy.2)The study of UPFC based on group technology of multiple,respectively to analysing the parallel side TNP-STATCOM,serial TNPC-SSSC,the control strategy of SSSC and simulation in Matlab/2016 b environment simulation model is established.The MMC-UPFC is then analyzed and the simulation model of the MMC-UPFC parallel is given.The simulation results are analyzed,and the power of UPFC is strong and the power of reactive power is obtained.3)The last section introduces the design and selection of relevant component parameters in the design and circuit of MMC type converter.From MMC inverter prototype of sub module design,this paper gives the child module calculation formula of capacitance parameters selection,and then compared the selection of bridge arm reactor parameters formula,and then type of MMC inverter experimental prototype made overall in this paper,the control system design.