海上风电场直流并网系统若干问题研究

发布时间：2018-02-05 22:34

本文关键词： 模块化隔离型DC/DC 海上风电场并网模块化多电平换流器限流模型子模块故障硬件搭建　出处：《浙江大学》2017年硕士论文　论文类型：学位论文

【摘要】：进入21世纪,环境问题又一次成为全球关注的问题,近年来雾霾问题也成为民众较为关注的焦点,电力改革、能源结构的调整势在必行。在《中华人民共和国国民经济和社会发展第十三个五年规划纲要》中,能源领域会开始实施结构调整,到2020年,非化石能源的比重将增加至15%,2030年增加至30%,而风能作为资源储量大、地域分散性等特点,成为新能源领域备受关注的发电方式,而其中尤以海上风电备受瞩目。中国拥有地域辽阔的海上领土和海岸线,对于海上风电的研究近年来处于稳步增长的态势,因此,研究海上风电场并网系统具有重要意义。本文提出应用于海上风电的模块化隔离型DC/DC变换器(Modular Isolated DC Converter,MIDC)结构,以及结合模块化多电平换流器(Modular Multilevel Converter,MMC)在逆变器中的应用,作了相关研究。针对所构建的海上风电并网系统,深入分析了所提出的模块化隔离型DC/DC换流器,的拓扑结构、工作原理,重点研究了模块化隔离型DC/DC的子模块故障问题,提出了子模块故障的冗余保护策略;提出三种备用方式,并且针对备用方式分析了冗余保护的各种工况;结合海上风电并网维护的不便性,提出了子模块故障个数的监测策略,建立了相应的数学模型,并在PSCAD中对于子模块故障进行了仿真验证。考虑到所构建系统主要适用于大容量、高电压的海上风电并网系统,因此对于岸上逆变侧也做了相关重点研究。由于电压等级较高,因此采用模块化多电平换流器作为逆变侧的主要结构,在传统最近电平逼近调制策略(Nearest Level Modulation,NLM)基础上提出了能够抑制二倍频环流的改进型策略,并在所搭建的仿真系统上进行了稳态和暂态的仿真验证。海上风电并网系统远离海岸线,需要较高的可靠性以及稳定性,同时尽量减少故障对电力电子器件的危害,故考虑在岸上逆变器交流出口侧串入故障限流器(Fault Current Limiting,FCL),并构建了相关的仿真模型,分析了故障限流器的工作原理及其对系统拓扑及运行状态的影响,并进行了稳态、暂态以及故障状况下的仿真验证。最后,介绍了所搭建的2250W的九子模块模型,分模块介绍了电路结构以及相关器件的选型依据,同时对DSP的相关控制程序进行了解读,对于模型样机进行了实验测试。
[Abstract]:In 21th century, the environmental problem has once again become a global concern. In recent years, haze has also become the focus of attention of the public, electricity reform. The readjustment of the energy structure is imperative. In the outline of the 13th Five-Year Plan for the National Economic and Social Development of the people's Republic of China, the energy sector will begin to implement structural adjustment by 2020. The proportion of non-fossil energy will increase to 15% and 30% in 2030. Wind energy, as a characteristic of large resource reserves and geographical dispersion, has become the most concerned power generation method in the field of new energy. Among them, offshore wind power has attracted much attention. China has a vast sea territory and coastline, the research on offshore wind power is growing steadily in recent years, therefore. It is of great significance to study the grid connection system of offshore wind farm. This paper presents a modular isolated DC/DC converter for offshore wind power. Modular Isolated DC Converter. The structure of MIDC and the application of modular multilevel converter (Modular Multilevel converter MMC) in inverter. According to the grid connection system of offshore wind power, the topology and working principle of the modular isolated DC/DC converter are analyzed in depth. The submodule fault of modular isolated DC/DC is studied, and the redundancy protection strategy of sub-module fault is proposed. Three kinds of standby modes are put forward, and the various conditions of redundancy protection are analyzed. Combined with the inconvenience of offshore wind power grid connection maintenance, the monitoring strategy of the number of sub-module failures is put forward, and the corresponding mathematical model is established. The sub-module fault is simulated and verified in PSCAD. Considering that the system is mainly suitable for large capacity and high voltage offshore wind power grid connection system. Because of the high voltage level, the modular multilevel converter is used as the main structure of the inverter side. Based on the traditional nearest level approach modulation strategy (nearest Level Modulation NLMs), an improved strategy is proposed to suppress the second harmonic loop. The simulation results of steady and transient state are given in the simulation system. The offshore wind power grid connection system is far from the coastline and needs high reliability and stability. At the same time, the harm of fault to power electronic devices is minimized, so the fault Current limiting FCLs are considered to be connected to the fault current limiter at the AC outlet of the shore inverter. The related simulation model is constructed, the working principle of the fault current limiter and its influence on the topology and operation state of the system are analyzed, and the simulation results of steady state, transient state and fault state are carried out. Finally, the simulation is carried out. This paper introduces the Nine sub-module model of 2250W, introduces the circuit structure and the selection basis of related devices, and interprets the related control program of DSP. The model prototype is tested experimentally.
【学位授予单位】：浙江大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TM614

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