【作者】 陈家伟；

【导师】 龚春英；

【作者基本信息】 南京航空航天大学 ， 电力电子与电力传动， 2013， 博士

【摘要】 风力发电作为可再生能源发电中发展最为迅速的技术之一，因其资源丰富和技术优势，已成为当前国内外研究和发展的重点。除了发展大型风力发电机组外，还需要发展中小功率等级风力发电技术以改善偏远地区用户用电困难的现状以及满足分布式发电、智能微电网的发展。中小功率等级机组的研究目标为增加机组捕获的功率，提高机组的可靠性、延长使用寿命，最大限度地降低机组单位发电功率所需的成本。然而，由于中小型风力发电机组通常采用定桨距结构，桨距角固定不可调节，机组在高风速区运行时限功率实现困难，容易发生过载损坏；且机组在运行过程中还承受了由风剪、塔影效应以及湍流风等引起的动态载荷，机组传动链易疲劳损坏。因此，本文围绕机组的全风速范围功率控制和载荷抑制策略展开了深入的研究。本文首先讨论了所采用的机组结构，并将其等效为两质量块进行了建模。通过对模型的分析，掌握了机组在全风速范围内的工作特性，为后文研究功率控制策略中调节器的设计奠定了理论基础。此外，通过模型分析找到了机组的固有谐振频率点，为后文对机组进行阻尼设计提供了理论支撑。接着，为了提高风力发电机组的年发电量，保证机组在全风速范围内安全运行，针对目前常用的最大功率跟踪（MPPT）控制策略存在通用性差且跟踪速度随着风速的变化而变化等问题，先后提出了一种具有较强通用性的MPPT控制方法和维持MPPT控制带宽恒定的方法，大大优化了机组的MPPT运行性能；其次，针对定桨距机组在高风速区恒功率控制实现困难的问题，提出了恒功率控制策略，并针对机组在高风速区运行时存在稳定性差的问题提出了相应的解决方案。运用本文所提出的功率控制策略，可在全风速运行范围内对机组实施功率优化控制。随后，针对机组运行时承受动态载荷大而影响其寿命的问题，本文对传动链载荷产生的源头展开了分析，详细地探讨了各类载荷的抑制策略：针对由机组跟踪转速指令引起的瞬态载荷，提出了跟踪带宽的优化设计原则，达到了机组捕获能量和承受载荷的合理平衡；针对风轮叶片对三维风场的旋转采样引起的转矩脉动，提出了阻尼注入的控制方法，有效地抑制了机组的气动载荷；针对过渡载荷，提出了软失速控制方法，使机组承受的过渡载荷较常规失速下降了近80%；而对于采用二极管不控整流的微型、小型风力发电机组，提出了一种低成本的高频载荷抑制策略，使高频载荷得到了大大的衰减。最后，建立了一台10kW的离网风力发电系统，并基于该系统对本文提出的功率控制和载荷抑制策略进行了实验验证。针对离网系统中存在的能量管理问题，提出了一种简单的能量管理策略，不仅实现了向用户不间断供电，而且使系统中蓄电池的充放电周期得到了优化。为了完善离网风力发电系统，本文最后对风力机的启动、停机、偏航、解缆等辅助功能的实现方法进行了分析，给出了实现方法。更多还原

【Abstract】 Among various kinds of renewable energy generation techniques, wind energy is by far the fastestgrowing energy for its abundant resources and maturity of turbine techniques; and, it has become aresearch focus and priority all over the world. To meet the electricity needs of the people in remoteareas and to support the developing of distributed generation and microgrids, it is more important todevelop the small-to medium-scale wind energy conversion system (WECS) rather than thelarge-scale ones. The essential control goal for small-to medium-scale WECS is to minimize the costof per generated power. To achieve this, optimum power control should be applied to the WECS.However, for the turbine structure is usually chosen as fixed-pitch concept, it has problems onlimiting the turbine power at high wind velocities and sustaining high dynamic load acting on theturbine shaft, which will shorten the service life of the system. Thus, the main contribution of thispaper is to lead a deep analysis to the power control and dynamic load reduction techniques for small-to medium-scale wind turbines.The turbine structure is firstly chosen in this paper, and then it is modeled as a two-mass model.The characteristics of the turbine operating in the full wind velocity range is obtained, which doeshelp to design the regulator and damping controller of the turbine.Then, to increase the annual energy yield and to comfirm its safety, a new maximum power pointtrcking (MPPT) control strategy, which can achieve unified control performance, is proposed in thispaper. Then, to solve the problem that the tracking speed is low and varies with wind velocity existedin the conventional OP control method, method to make the tracking bandwidth constant is proposed.With the proposed method, it is possible to conduct a systematic design procedure on the MPPTcontrol strategy. To compensate the reliability of the system at high wind velocities, a newcompensation method is also proposed in this paper. With the proposed method, constant poweroperation is realized.Besides the power control strategy, the dynamic load reduction rechniques are also required toincrease the service life of the system, thus to reduce the system cost. In this paper, the dynamic loadsare categoried in four parts according to their souces. And the corresponding strategies to reduce theloads are also discussed in detail: To optimize the transient load produced during MPPT process, theMPPT bandwidth is optimally designed with the constant bandwidth MPPT method proposed. Thesystem control with damping injection method is then proposed to reduce the aerodynamic loadcaused by wind shear and tower shadow and to get rid of the vibration operation mode. In addition, to reduce the transit load under turbulence, soft-stall control method is proposed, with which the transitload can obtain a nearly80%reduction compared with the passive stall method. Moreover, to reducethe high frequency load induced by the current harmonics generated by the diode rectifier, a low costdamping method is also proposed. All the dynamic load reduction methods proposed are beingdiscussed in detail in this paper.Finally, a10kW stand-alone WECS is established in the laboratory. The power control and dynamicload reduction method as well as a new decoupled energy management mechanism are all employedin this system. The good performance of the proposed method is validated by the experimental results.In addition, to set an example on how to conduct a whole stand-alone WECS, the start/stop procedure,yaw and untwist system are all illustrated at the end of this paper.更多还原