基于模块化多电平换流器的柔性多状态开关控制研究-原理及建模

南京工程学院电力工程毕业设计（论文）AbstractWith the continuous development of energy transformation in China,a largenumber of distributed power sources will be widely connected to the distributionnetwork,which will bring problems such as voltage overload,bidirectional power flowand feeder power imbalance.Due to the weak structure of distribution network in China,closed-loop design and open-loop operation are mostly adopted,leading to the failure oftraditional control methods to effectively solve the above problems.However,it hasbecome an important trend to use power electronics technology to upgrade andtransform distribution network.As a new device based on power electronics technology,Soft Open Point (SOP)is used to replace the conventional contact switch,which canflexibly regulate the power flow of feeder lines of distribution network,improve thevoltage distribution level and enhance the absorption capacity of distributed powersupply of distribution network.As a new type of high voltage and high power topology,modular multilevelconverters not only get wide attention in the field of DC power transmission,but alsohave great prospects in the field of high voltage frequency conversion.Compared withthe traditional high voltage converter topology,the modular multilevel converter showsa series of technical advantages in flexibility,voltage waveform quality,reliability,voltage power level and other aspects.The topology of Modular Multilevel Convertercan meet the requirements of SOP in distribution network from both economic andtechnical aspects.SOP based on MMC topology structure can meet the requirements ofasynchronous interconnection of feeder lines with multiple voltage levels in the futuredistribution network,making the future distribution network more flexible,efficient andreliable.In this paper,the SOP based on Modular Multilevel Converter (MMC)isstudied.The principle,topological structure and mathematical model of MMC arestudied.The principle,characteristics,topology structure and mathematical model ofSOP.Finally,the simulation model of SOP control research based on MMC isestablished and analyzed.