双馈式风电机组建模及低电压穿越技术研究

发布时间：2018-11-06 08:24

【摘要】：近些年来,风电发展依然迅速,装机容量不断增加,风电已成为我国能源结构中的重要组成部分。风电的并网稳定运行以及应对电网故障的能力是目前亟待解决的问题。论文针对电网故障期间对变流器保护的需求开展研究。开展的主要研究工作有:建立了双馈风电系统各主要组成部分,包括风轮,传动链,发电机和变流器的数学模型。其中,对双馈电机和变流器模型进行了详细分析,根据坐标系转换方法,推导得到两相旋转坐标系下的数学模型,为后续控制策略的设计仿真奠定基础。分析了双馈风电机组的变流器控制策略,建立了相应的控制器模型,仿真分析了电网故障期间风电机组各参数的变化。在传统控制策略基础上,分析了故障发生时定子励磁电流变化对双馈风电机组暂态运行特性的影响,仿真分析了不同故障深度下该改进控制的适用性,仿真结果表明该控制方法对抑制过电流有一定作用,但在较深的电网故障下,控制有一定的局限性。根据现有研究,建立了超级电容过压保护电路的详细模型,并仿真分析了电路的充放电特性以及过压保护能力。仿真实验结果表明,超级电容保护电路具有良好的充放电特性,且能够较好地抑制直流母线电压波动,提供低电压故障期间对机组直流母线的过压保护。此外,文中总结了超级电容容值以及线路电感的估算方法,并分析了电感参数对充放电电流的影响,为设备选型提供一定的指导。
[Abstract]:In recent years, wind power is still developing rapidly and the installed capacity is increasing. Wind power has become an important part of energy structure in China. The stable operation of wind power grid and the ability to deal with power grid faults are urgent problems to be solved. This paper focuses on the needs of converter protection during the fault period of power grid. The main research work is as follows: the mathematical models of wind turbine, transmission chain, generator and converter are established. The model of doubly-fed machine and converter is analyzed in detail. According to the method of coordinate transformation, the mathematical model of two-phase rotating coordinate system is derived, which lays a foundation for the design and simulation of subsequent control strategy. The converter control strategy of doubly-fed wind turbine is analyzed, the corresponding controller model is established, and the variation of wind turbine parameters during the fault period of power grid is simulated and analyzed. On the basis of traditional control strategy, the influence of stator excitation current variation on transient operation characteristics of doubly-fed wind turbine is analyzed, and the applicability of the improved control under different fault depth is analyzed. The simulation results show that this control method has certain effect on restraining overcurrent, but it has some limitations in the case of deep power network fault. According to the existing research, a detailed model of super capacitor overvoltage protection circuit is established, and the charge-discharge characteristics and over-voltage protection ability of the circuit are simulated and analyzed. The simulation results show that the super capacitor protection circuit has good charge-discharge characteristics and can restrain DC bus voltage fluctuation and provide overvoltage protection for DC busbar during low voltage fault. In addition, the method of estimating the capacitance of super capacitor and line inductance is summarized, and the influence of inductor parameters on charge-discharge current is analyzed, which provides some guidance for equipment selection.
【学位授予单位】：华北电力大学(北京)
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TM315

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