海上风电RMC-HVDC系统协调控制策略研究

发布时间：2018-05-12 04:20

本文选题：精简矩阵变换器 + 海上风电-高压直流输电　；参考：《湘潭大学》2014年硕士论文

【摘要】：海上风力发电-高压直流输电(high voltage direct current，HVDC)系统是风力发电及其功率传输技术的发展方向。由于海上运输、安装、维护的成本较高，这就要求海上风电-高压直流输电系统的核心环节——换流器，具有高集成度、高可靠性和高效率等特点，并且还需要考虑新的换流器拓扑结构和控制策略来减少投资和运行成本。精简矩阵变换器(reduced matrix converter，RMC)是一种从传统矩阵变换器拓扑中衍生出来的新型功率变换器，由其构成的RMC高频链换流器具有转换级数少、功率密度高、效率高和可靠性高等优点，因而在海上风电-高压直流输电系统中有着极大的应用前景。近年来各国学者以海上风电-高压直流输电为应用背景，对RMC高频链换流器的拓扑结构和调制策略等方面进行了研究，并取得了一定的成果。风速的波动性导致风电场输出的有功功率不稳定，交流系统故障等情况会使得岸上逆变器输出有功功率受限而造成直流母线电压泵升，危及设备的安全运行。然而，对各种工况和故障情况下海上RMC-岸上电压源换流器(voltage source converter，VSC)协调控制策略的研究，以保证高压直流输电系统送受端有功功率传输平衡，国内外尚未见到相关报道。此外，基于RMC高频链换流器的串联多端海上风电-高压直流输电系统无需海上升压变压器即可提升电压等级，减少了系统的尺寸和重量，提升了系统的功率密度和效率。本文首先详细分析了电压型RMC的双极性电压空间矢量调制(bipolar voltage spacevector pulse-width modulation，B-V-SVM)策略，并推导了输入电压和输出电压之间的数学关系。第二，提出了基于RMC的直驱海上风电-高压直流输电系统控制策略，实现了最大风能跟踪(maximum power point tracking，MPPT)、直流稳压控制以及并网有功/无功功率解耦控制。为提高该系统的低电压穿越(low-voltage ride-through，LVRT)能力，，提出了基于有功功率指令修正的RMC高频链换流器功率协调控制策略，并结合变桨距角控制实现了高压直流输电系统海上RMC-岸上VSC的协调控制，在岸上电网电压跌落时保持高压直流输电系统送受端有功功率传输平衡。第三，提出了基于RMC高频链换流器的串联多端海上风电-高压直流输电系统拓扑结构及其协调控制策略，该控制策略由风电场监测控制(wind farm supervisory control，WFSC)、海上风电机组控制和网侧并网控制组成，并采用最优直流电流参考算法。在系统正常运行时，该控制策略可实现各风电机组独立最大风能跟踪控制、直流电流控制和并网有功/无功功率解耦控制；在风电机组故障和电网电压波动等情况下保证系统安全高效运行。最后，搭建了基于RMC的直驱海上风电-高压直流输电系统控制策略仿真模型并进行了仿真验证，仿真结果验证了所提拓扑结构及其控制策略的正确性和可行性。
[Abstract]:Offshore wind power generation-high voltage direct current (HVDC) system is the development direction of wind power generation and its power transmission technology. Because of the high cost of sea transportation, installation and maintenance, the core link of offshore wind power and HVDC transmission system is converter, which has the characteristics of high integration, high reliability and high efficiency. We also need to consider new converter topology and control strategy to reduce investment and operation costs. Reduced matrix converter (RMC) is a new type of power converter derived from the traditional matrix converter topology. It has the advantages of less converters, high power density, high efficiency and high reliability. So it has great application prospect in offshore wind power-HVDC transmission system. In recent years, scholars in various countries have studied the topology and modulation strategy of RMC high-frequency chain converter with the background of offshore wind power-HVDC transmission, and have achieved certain results. The fluctuation of wind speed leads to the instability of the active power output from the wind farm, and the failure of the AC system makes the DC bus voltage pump rise due to the limitation of the active power output of the shore inverter, which endangers the safe operation of the equipment. However, the coordinated control strategy of marine RMC-shore voltage source converter (RMC-shore voltage source converter) under various working conditions and faults is studied to ensure the balance of active power transmission at the receiving end of HVDC transmission system, which has not been reported at home and abroad. In addition, the series multi-terminal offshore wind power-HVDC transmission system based on RMC high-frequency chain converter can raise the voltage level without the need of offshore booster transformer, reduce the size and weight of the system, and improve the power density and efficiency of the system. In this paper, the bipolar voltage spacevector pulse-width modulation- B-V-SVM strategy of voltage source RMC is analyzed in detail, and the mathematical relationship between input voltage and output voltage is derived. Secondly, the control strategy of direct-drive offshore wind power-HVDC transmission system based on RMC is proposed, which realizes maximum power point tracking control, DC voltage stabilizing control and active / reactive power decoupling control. In order to improve the low-voltage traversing low-volride-through-LVRTs of the system, a coordinated power control strategy for RMC high-frequency chain converter based on active power instruction correction is proposed. Combined with variable pitch angle control, the coordinated control of offshore RMC-shore VSC of HVDC transmission system is realized, and the balance of active power transmission at the receiving end of HVDC transmission system is maintained when the voltage drops on shore. Thirdly, the topology structure and coordinated control strategy of series multi-terminal offshore wind power-HVDC transmission system based on RMC high-frequency chain converter are proposed. The control strategy is composed of wind farm monitoring control farm supervisory control wind turbine control and grid side grid-connected control. The optimal DC current reference algorithm is adopted. When the system is running normally, the control strategy can realize the independent maximum wind power tracking control, DC current control and decoupling control of active and reactive power. The safe and efficient operation of the system is ensured under the condition of wind turbine fault and voltage fluctuation of power grid. Finally, the control strategy simulation model of direct-drive offshore wind-HVDC system based on RMC is built and verified. The simulation results verify the correctness and feasibility of the proposed topology and control strategy.
【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

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