基于RMC的海上风电并联多端高压直流输电研究

发布时间：2018-01-17 03:03

本文关键词：基于RMC的海上风电并联多端高压直流输电研究　出处：《湘潭大学》2014年硕士论文　论文类型：学位论文

【摘要】：海上风电场资源丰富、环境污染少、风速稳定、低湍流、风切变小，近年来已成为世界各国可再生能源发展领域的焦点。对于远距离海上风电能量传输，采用高压直流传输方式要比交流传输更经济、更可靠和更稳定，海上风电高压直流传输是未来风力发电及其能量传输的重要发展方向。随着海上风电场装机容量的不断加大，受传输距离、维护成本等因素的影响，加上风电机组选址困难、适用于换流站建设的空间有限，这就需要换流器有尽量小的体积，便于安装，较轻的重量，便于海上运输。另外考虑到海上环境的复杂型，海上风电场需要换流器具有更高的可靠性。精简矩阵变换器是一种新型能量转换器，英文全称为reduced matrixconverter，简称为RMC。它具有结构紧凑、控制自由度大、输入/输出性能优良等特点。由RMC构成的换流器具有转换级数少、高功率密度、高可靠性和高效率等优点，是海上风电-HVDC系统中一种颇具潜力的换流器。近年来各国学者在RMC换流器的调制策略、换流技术、损耗分析以及在海上风电-HVDC系统中应用等方面展开研究，取得了一定的研究进展。但基于RMC的海上风电-HVDC系统以双端口拓扑为主，，对于其控制策略的研究也只是对其中的一个端口进行研究（海上RMC换流器端口或者岸上并网换流器端口）。未对RMC-HVDC系统各种工况和电网故障情况下系统协调控制做出深入分析。文章对RMC换流器的拓扑结构进行了分析，介绍了电流型和电压型RMC换流器各自的特点，深入分析了RMC双极性电压空间矢量调制策略，建立了基于RMC的海上风电并联多端高压直流输电系统，提出了相应的控制策略，通过对RMC换流器的控制实现了最大风能捕获，HVDC岸上逆变器对并网有功功率和无功功率实现了解耦控制。针对电网电压跌落时引起的HVDC系统有功功率传输不平衡问题，利用超级电容器的快速充放电能力，提出了超级电容器储能端口双向DC-DC变换器的控制策略，DC-DC变换器根据直流电压变化实时对超级电容进行充电，使HVDC系统传输的有功功率达到动态平衡，有效提高了海上风电-HVDC系统的低电压穿越能力，增强了系统的可靠性和稳定性。通过仿真验证了所提控制策略的正确性和有效性。
[Abstract]:Offshore wind farms are rich in resources, less environmental pollution, stable wind speed, low turbulence, small wind shear, in recent years has become the focus of renewable energy development in the world. Using HVDC transmission mode is more economical, more reliable and more stable than AC transmission. High voltage DC transmission of offshore wind power is an important development direction of wind power generation and its energy transmission in the future. With the increasing installed capacity of offshore wind farm, it is affected by transmission distance, maintenance cost and other factors. In addition, the location of wind turbine units is difficult, and the space for converter station construction is limited, which requires the converter to have as small a volume as possible, easy to install, lighter weight. In addition, considering the complexity of marine environment, offshore wind farm requires a higher reliability of converters. Reduced matrix converter (RMC) is a new type of energy converter, which is called reduced matrix converter (RMC). It has compact structure and large control degree of freedom. The converter composed of RMC has the advantages of less conversion series, high power density, high reliability and high efficiency. It is a potential converter in offshore wind power HVDC system. In recent years, many scholars in the world in the RMC converter modulation strategy, commutation technology. Some research progress has been made in loss analysis and application in offshore wind power HVDC system, but the offshore wind power HVDC system based on RMC is based on dual-port topology. The study of control strategy is only one of the ports (offshore RMC converter port or shore grid-connected converter port). The coordinated control of RMC-HVDC system under various operating conditions and power network failures is not analyzed in depth. In this paper, the topology of RMC converter is analyzed, the characteristics of current mode and voltage type RMC converter are introduced, and the RMC bipolar voltage space vector modulation strategy is deeply analyzed. A parallel multi-terminal HVDC transmission system for offshore wind power based on RMC is established, and the corresponding control strategy is proposed. The maximum wind power capture is realized by controlling the RMC converter. The HVDC shore inverter realizes decoupling control of active power and reactive power in grid-connected system. Aiming at the unbalanced transmission of active power in HVDC system caused by voltage drop of power grid. The control strategy of bi-directional DC-DC converter for supercapacitor energy storage port is proposed by using the fast charge-discharge capability of supercapacitor. According to the DC voltage change, the DC-DC converter charges the super capacitor in real time, which makes the active power transmission of the HVDC system achieve dynamic balance. The low voltage traversing ability of offshore wind power HVDC system is improved effectively, and the reliability and stability of the system are enhanced. The correctness and effectiveness of the proposed control strategy are verified by simulation.
【学位授予单位】：湘潭大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TM614;TM721.1

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