【作者】 李磊；

【导师】 陶骏； 陶磊；

【作者基本信息】 安徽大学 ， 电气工程（专业学位）， 2021， 硕士

【摘要】 随着社会的发展,能源危机问题愈发严重,大力发展新能源是解决问题的有效途径。核聚变能是一种储量丰富且无污染的新能源,多年来,国内外持续开展了相关的科学与工程技术研究。在建的ITER(International Thermonuclear Experimental Reactor)装置旨在建造一个可持续燃烧的Tokamak型聚变实验堆,以验证聚变反应堆的技术可行性。电源系统是ITER装置中的重要组成部分,总安装容量达2200MVA,由法国400k V电网直接供电,通过降压和功率变换,驱动超导磁体及各类加热系统,实现等离子体的产生、驱动、加热及控制。由于聚变负荷的强动态特性,带来了高压电网的巨大的有功及无功功率冲击,冲击功率在一个工频周期内幅度可高达百MW/Mvar,且具有很强的随机性,威胁到聚变装置、电网的安全稳定运行。为此,ITER配套了相应的无功补偿装置,以期实现改善电网工作条件,实现电源系统与电网的兼容。然而,当前的功率补偿系统难以应对ITER未来高参数运行条件。本文围绕ITER电源系统的冲击性负荷功率补偿问题,分析了电源系统中有功/无功功率扰动特性;针对现有无功补偿容量不足、动态性能不佳及有功冲击无应对等问题,融合超级电容储能与模块化多电平变换技术,建立了基于超级电容储能型模块化多电平变换器(Supercapacitor Energy Storage System Based on Modular Multilevel Converter,MMC-SC)的冲击功率补偿方案及控制策略,并实现与现有的无功功率补偿系统的协同,具体研究内容如下:首先,结合ITER装置运行过程,对ITER系统运行时典型负荷进行分析,明确了各类运行工况下冲击功率的特征;通过Matlab仿真实验探究了冲击性功率扰动下,电网电压跌落、发电机转速波动以及电网功率强迫振荡等现象;针对ITER系统功率补偿所面临的问题,提出了基于储能型多电平变换器技术的冲击功率解决思路。其次,对MMC-SC的拓扑结构、数学模型及补偿原理进行了研究;为实现良好的补偿性能,分析了MMC-SC的调制策略,设计了MMC与双向DC/DC变换器协同控制策略及子模块电容电压控制策略,实现了MMC-SC对系统有功/无功功率的快速补偿,并通过三层能量均衡控制策略实现超级电容荷电状态的有效控制。为提高系统容错运行能力,采用了一种动态热备用的容错控制策略,通过减小冗余模块与正常模块的电压差值,降低了因冗余投入时充电过程产生的暂态影响。最后,面向ITER工程应用,通过对ITER电源系统配电网系统分析,确定了MMC-SC在ITER系统中的安装点,并结合典型运行负荷,设计了MMC-SC系统的主要参数;针对MMC-SC与ITER已有的SVC装置的协调运行问题,设计了两者协同控制方法,为ITER系统高参数运行模式下冲击功率的补偿提供了有效方案。本文所提方案及控制策略均通过仿真进行了验证,该技术可为ITER电源系统冲击功率补偿问题提供参考,同时对我国未来开展国内核聚变反应堆的自主设计具有借鉴意义。更多还原

【Abstract】 With the development of society,the problem of energy crisis is becoming more and more serious.Developing new energy is an effective way to solve the problem.Nuclear fusion energy is a kind of abundant and pollution-free new energy.O ver the years,relevant scientific and engineering technology research has been continuously carried out at home and abroad.The International Thermonuclear Experimental Reactor(ITER)is designed to build a sustainable combustion Tokamak fusion experimental reactor to verify the technical feasibility of the fusion reactor.The power supply system is an important part of ITER device,with a total installed capacity of 2200 MVA.It is connect to French 400 k V power grid,through step-down transformers and power conversion,and realizes the generation,driving,heating and control of plasma by driving superconducting magnets and various heating systems.Due to the strong pulse characteristics of fusion load,it brings a huge impact of active and reactive powers to the high voltage power grid.The impact power can reach several hundreds MW/Mvar in one power frequency cycle,and has strong randomness,which threatens the safe and stable operation of fusion device and power grid.Therefore,ITER is equipped with corresponding reactive power compensation devices,in order to improve the working conditions of the power grid and realize the compatibility between the power supply system and the power grid.However,the current power compensation system cannot cope with the high-parameter operating conditions of ITER in the future.Thesis focuses on the impact power compensation problem of ITER power supply system,and analyzes the perturbation characteristics of active and reactive power in the power supply system.Aiming at the problems of insufficient reactive power compensation capacity,poor dynamic performance and lack of active power impact compensation,the impulse power compensation scheme and control strategy of supercapacitor energy storage system based on modular multilevel converter(MMC-SC)are established,combined with the technology of supercapacitor energy storage and modular multilevel converter.The cooperative control with the existing reactive power compensation system is further realized.The specific research contents are as follows :First of all,according to the operation p rocess of ITER device,this paper analyzes the typical load of the ITER system during operation,and clarifies the characteristics of the impulse power under various operating conditions.Through the Matlab simulation experiment,the phenomena of the grid voltage sags,generator speed fluctuation and forced oscillation of grid power and others are researched.Aiming at the problems of power compensation in ITER system,a solution of impulse power based on energy storage multilevel converter technology is proposed.Secondly,the topology,mathematical model and compensation principle of MMC-SC are studied.In order to achieve good compensation performance,the modulation strategy of MMC-SC is analyzed,and the submodules capacitor voltage control strategy and the cooperative control strategy of MMC and bidirectional DC/DC converter are designed respectively.As a result,MMC-SC can quickly compensate the active and reactive impact power of the system.In order to improve the fault-tolerant operation ability of the system,a fault-tolerant control strategy of dynamic active standby is adopted,by reducing the voltage differences between the redundant module and the normal module,the transient effect of charging process caused by redundant switching is reduced.Finally,the installation point of the MMC-SC in the ITER system is determined considering the engineering application.According to the impact power caused by typical operation load,the main parameters of MMC-SC system are designed.Aiming at the problem of coordinated operation of MMC-SC and ITER existing SVC devices,the cooperative control method is designed,which provides an effective scheme for the impact power compensation of ITER system under high parameter operation mode.The scheme and control strategy proposed in this paper are verified by simulation.The technology can provide a reference for ITER power supply system impact power compensation,and also has a reference significance for China to carry out the independent design of domestic nuclear fusion reactor in the future.更多还原