【作者】 战亮宇；

【导师】 金新民；

【作者基本信息】 北京交通大学 ， 电力电子与电力传动， 2012， 博士

【摘要】 随着新能源产业的发展,双馈发电系统被广泛应用于大功率风力发电中。研究双馈型风力发电系统的工作原理及存在的问题对于新能源的利用有重要意义。双馈电机定、转子与各自所连接的电源均有有功功率和无功功率的交换,其机电能量转换过程中功率关系复杂。本文对转子电路频率符号的问题和无功功率特性进行了研究,指出了超同步运行转子频率取负值的必要性和物理意义,指出应用双馈电机等效电路计算转子无功功率时出现的“无功功率变性”现象；对双馈电机等效电路进行了与物理部分一一对应的划分,明确了其中代表转轴作用的等效元件并将其消耗的无功功率定义为机械无功功率,在此基础上解释了能量转换过程中无功功率的流动特点和守恒特性；避开复杂而不直观的表达式,采用四维图的形式直观地表现了双馈电机在整个三维工作区间的运行特性。双馈电机能量转换过程由连接在转子和电网之间的背靠背变流器来控制。本文建立了双馈电机数学模型和网侧变流器数学模型,分别构建了网侧变流器电压定向矢量控制策略和机侧变流器定子磁链定向矢量控制策略,实现了背靠背变流器的有功功率和无功功率解耦控制；分析对比了双馈电机并网前后数学模型,指出并网前后耦合项和电流调节器参数设置的差异；说明了忽略并网前后数学模型变化对双馈电机转矩动态性能设计和调试带来的不利影响；构建了带电压闭环的双馈电机并网控制策略,在该策略中耦合项和电流调节器参数并网前后保持不变,从并网前后差异的角度对该控制策略进行了分析和实验研究。在定子磁链定向的双馈风力发电控制系统中,定子磁链准确与否直接关系到双馈电机有功功率和无功功率能否被准确控制。在电网电压跌落期间,定子磁链中出现直流分量和负序分量,且磁路出现非线性现象,此时就对定子磁链检测方法提出了更为苛刻的要求。本文对定子磁链检测的直接计算法和闭环计算法的原理进行了分析,着重研究了各种方法在低电压穿越期间的动态性能。对不同方法应用于低电压穿越控制时,系统的低电压穿越能力进行了实验研究和结果分析,为LVRT控制中定子磁链检测方法的选取提供了依据。转子位置的准确获得是双馈电机矢量控制的必要条件。本文分别研究了有位置传感器和无位置传感器两种情况下转子位置检测方法。对于有位置传感器的情况,提出了同步旋转坐标系中编码器安装位置的直接计算法,避免了对并网前含有大量高频分量的定子电压相位的检测,减小了编码器安装位置检测运算量。在无位置编码器的情况下,控制系统需采用无位置算法先计算出转子位置,然后才能实施矢量控制。本文分析了无位置编码器运行的开环算法和闭环算法,着重研究了基于定子磁链和转子电流的模型参考自适应算法,通过对其等效闭环结构的分析证明了这两种方法的同一性；对基于转子电流的模型参考自适应算法中自适应PI调节器的输入信号进行了改进,使得自适应PI调节器的输入误差与转子位置检测误差的成线性关系；推导了自适应PI调节器的参数计算方法,对不同参数下转子位置检测动态性能进行了实验研究。更多还原

【Abstract】 Along with the development of new and renewable energy industry, doubly-fed induction machine wind power generation systems are widely used in large wind power generation occasions. Research of the principle and existing problems of doubly-fed induction machine wind power generation system is really meaningful to renewable energy application.Both the stator and rotor of (DFIM) exchange active and reactive power with the sources connected to them, so the power relationship in the energy conversion is complicate. This dissertation analyses rotor’s algebraic sign and reactive power, and give the necessity of minus frequency in super-synchronous speed area. The physical meaning of minus frequency is illustrated. When reactive power is computed by equivalent circuit,"reactive power character change" phenomenon occurs. The equivalent circuit of DFIM is divided according related physical element. The mechanical shaft related element is defined, so its reactive power. Then the reactive power flow and conservation character in energy conversion is illustrated. Instead of complicated equation, four-dimensional figures are used to express DFIM working characteristics in three-dimensional area.The energy conversion of DFIM is controlled by back-to-back converters between its rotor and the grid. This dissertation builds mathematical models of back-to-back converters. Grid side converter’s grid voltage oriented vector control and machine rotor side converter’s staton flux oriented control are employed and the decoupled control of back-to-back converter’s active and reactive power is reached. The mathematical models of DFIM before and after grid connection are researched. The couple items and parameters of DFIM before and after grid connection are found different. The drawbacks of ignoring the difference of DFIM before and after grid connection in torque dynamic performance design and implement are illustrated. The grid connection scheme with voltage close loop is built and analyzed from the point of difference before and after grid connection. Then the corresponding experiment is done and the results are analyzed in comparison.In stator flux oriented vector control DFIM wind power generation system, the accuracy of complex power control is decided by stator flux detection performance. During low grid voltage period dc composition and negative sequence occurs in stator flux and magnetic circuit non-linear character occurs too. This puts more slashing requirements on stator flux detection algorithm. This dissertation analyzed the direct computation methods and close loop method of stator flux detection. The dynamic performance of different methods during low voltage ride through is emphasized. The system LVRT ability with different flux detection methods is researched in principle and experiments. The research provides groundwork in stator flux detection method choosing during LVRT.Rotor position is necessary in vector control of DFIM. This dissertation researches rotor position detection methods in both position sensor existing and position sensor non-existing conditions. In position sensor existing condition, a position sensor mounting detection method in synchronous reference frame is proposed. This method avoids phase judge of stator voltage before grid connection, which has a lot of harmonics. So the computation workload in position sensor mounting detection is reduced largely. In position sensor non-existing condition, the control algorithm has to compute rotor position firstly to implement vector control scheme. This dissertation researches open loop and close loop algorithm of rotor position detection. The model reference adaptive system based on stator flux and rotor current are analyzed in detail. Their equivalent close loop structure shows the sameness of the two algorithms. The input of adaptive mechanism in rotor current based MRAS is improved. As a result, the adaptive mechanism input has a linear relationship with rotor position detection error. The parameters design method is deduced for PI adaptive mechanism. The dynamic performance of system with different parameters is researched in experiment.更多还原