【作者】 向大为；

【导师】 杨顺昌；

【作者基本信息】 重庆大学 ， 电气工程， 2006， 博士

【摘要】 双馈感应发电机可实现变速恒频运行,具有优越的稳态和暂态运行性能以及相对较小的励磁容量,特别适用于风力、变水头水力发电以及抽水蓄能等可再生能源发电系统。适当的励磁控制策略是双馈感应发电机实现优良运行性能的关键,因此对双馈感应发电机励磁控制策略的研究一直都是国内外研究的重点。本论文主要针对一些特殊工况下双馈感应风力发电机的励磁控制策略进行了深入地研究。研究的主要内容包括:电网故障时双馈感应发电机不脱网运行的控制策略;双馈感应发电机与无辅助在线换流的晶闸管HVDC的协调控制策略以及双馈感应发电机的并网与解列控制策略等。论文首先建立了双馈感应发电机的空间矢量模型,利用该模型解析推导了双馈感应发电机暂态电磁关系,并结合数值仿真对双馈感应发电机的暂态物理过程进行了解释。研究结果表明:双馈感应发电机的定、转子电流以及电磁转矩取决于发电机内部的定、转子磁场。其中定子磁场受定子外加电压的影响,而转子磁场则可以通过转子电压进行控制。适当地控制转子励磁电压能够实现对发电机运行状态的控制。在理解电网短路故障时发电机的暂态物理过程的基础上,提出了电网短路故障时双馈感应发电机不脱网运行的励磁控制策略。为保证故障期间双馈感应发电机励磁变频器安全运行,新的励磁控制策略针对故障过程中发电机内部电磁变量的暂态特点,控制发电机转子电流产生的磁链(故障暂态时该磁通只通过漏磁路径,是漏磁链)以抵消定子磁链中的“有害”分量(暂态直流分量与负序分量)对转子侧的影响,与此同时,利用定子侧电阻最终对发电机进行灭磁。实验和大量的系统仿真验证了该控制策略的正确性,并分析了各种因素对控制效果的影响,为双馈感应发电机在电力系统中大规模应用奠定了基础。大型海上风电场是当前风力发电技术发展的主要趋势。论文针对海上输电的特点,提出了通过无辅助在线换流的晶闸管HVDC连接大型海上风电场并网的新方案,深入研究了无辅助在线换流的晶闸管HVDC与双馈感应发电机的协调控制策略,并对协调控制下风电场电压和频率调节特性以及换流站的电压稳定性进行了分析。研究结果表明:利用本文提出的协调控制策略,在满足晶闸管换流站在线换流要求的前提下,可以实现双馈感应风力发电机跟踪最大风能变速稳定运行。论文的研究为海上或远距离风电场接入电网提供一种技术、经济性能优越的新方案,为解决大型海上或远距离风电场并网技术提供理论依据。论文最后对双馈感应发电机并网及解列的控制策略进行了研究,提出了两种简便易行的并网(即准同期、自同期)新方案以及能效较高的解列方案,并通过数值更多还原

【Abstract】 The Doubly-fed Induction Generator (DFIG), which has features of variable speed operation, superior steady-state and transient-state operation characteristics and relatively small excitation rating, is especially suitable for the renewable energy generation such as wind power generation, hydropower generation with variable water head and pumping storage generation. As a key to achieve good performance during the DFIG operating, the excitation control strategies of the DFIG have being the focus of the research all over the world. Therefore, the excitation control strategies of the DFIG under some special operation modes were deeply studied in this dissertation, including the ride-through control of the DFIG under a grid fault, the coordinated control between a HVDC and the DFIGs in order to connect a wind farm into grid and the control methods of the DFIG under cut in or cut off operation.Firstly, the mathematic model of the DFIG expressed with space-vector was build. Then the transient electromagnetic relationship was derived and the transient physical process was explained combined with the analytic and simulation analyses. Research results show that the stator and rotor currents and air-gap torque are subjected to the stator and rotor flux fields in the generator. Where, the stator flux field is mainly constrained by the stator voltage which is decided by the outer operation condition of the machine. However the rotor flux field can be controlled by rotor voltage. Therefore, it’s possible to control the operation state of the DFIG with proper excitation regulation. Based on the deeply understanding of the DFIG transient under a grid fault, the ride-through excitation control strategy was proposed. To guarantee the safety of rotor side converter during the grid fault, the flux linkage produced by the rotor current, which goes through leakage flux path during the transient, is controlled to counteract the effect of the harmful components in the stator flux (including the transient DC flux and negative sequence flux components). At the same time, the stator side resistance is used to weaken the harmful stator flux field. The validity work has been done by experiments and system simulations, while the control performance influenced by different factors was analyzed in detail. The research work carried out in this dissertation is important for the large-scale application of the DFIG in power system.Currently, the offshore wind power is one of the mainstream developing trends of wind power technology. Based on the features of the offshore electrical power更多还原