【作者】 张文文；

【导师】 田德；

【作者基本信息】 华北电力大学 ， 动力工程， 2012， 硕士

【摘要】 大规模的风电并入电网之后,会对电网的稳定性产生显著的影响。永磁直驱风力发电系统以其特有的优点得到了广泛地应用。传动系统的轴系特性将导致机组在电网故障及恢复过程中扭矩等的振荡,对机组运行的稳定性产生影响,因此有必要对其进行研究分析。首先建立了永磁直驱风力发电系统各部分的数学模型并研究了变流器的控制策略。电机侧PWM变流器电流的控制采用id=0的控制策略,通过调节定子侧的dq轴电流,实现转速的调节及电机励磁与转矩的解耦控制。电网侧PWM变流器采用电网电压定向控制,实现了有功和无功的解耦控制。进而在PSCAD软件中搭建了2.5MW永磁直驱风电机组的仿真模型,并验证所建模型及控制策略的合理性。在所建立的仿真模型的基础上,假设出现三相对地故障,研究了两质量块传动系统特性对风力发电机组暂态稳定性的影响。仿真结果证明了,风轮惯性时间常数Hw、发电机惯性时间常数Hg的增加或是Hw/Hg的减小都将使得并入电网的有功功率及直流侧电压的振动幅值增大,稳定性降低。在研究机组暂态性能时,有必要考虑传动系统扭转轴的柔性特性的影响。等效弹簧刚度系数越大,机组的暂态稳定性越小。风轮与发电机各自的自阻尼与风轮与发电机之间的互阻尼对系统的暂态稳定性都将会产生影响,尤其是互阻尼的影响更是不能忽略,它能够提高系统的暂态稳定性。更多还原

【Abstract】 The large-scale wind power into the power grid must have a significant impact to the stability of the grid Permanent magnet direct-drive synchronous wind turbine system has been widely applied for its unique advantages. Transmission shafting flexible will lead to a unit in power grid fault and recovery process of torque oscillation, on the stability of unit operation effect, so it is necessary to research and analysis it.First, the mathematical model of permanent magnet direct driving wind power system is established and the control strategy of the converter is researched. The control strategy of id=0is researched in the motor side PWM. By regulating the stator current of dq axis to realize speed regulation and the decoupling control of motor excitation and torque. The voltage directional control is used in the Power grid side PWM converter and the coupling control of active power and reactive power is realized. The2.5MW wind generator of permanent magnet direct driving simulation model is built. The model and the control strategy are verified.Based on the built simulation model, supposing that there is three phase fault. The influence of transmission system characters on transient performances of wind turbine are researched. The simulation results prove that the increase of Hw、Hg or the decrease of Hw/Hg will both made the vibration amplitude of active power and dc voltage increase and the stability is reduced. It is necessary to consider the influence of the flexibility characteristics of the torsional axis of the transmission system when the transient performance is researched. The equivalent spring stiffness coefficient is bigger and the transient stability of the system is smaller. The self damping of wind turbine、the self damping of generator and the mutual damping of them are all have a significant impact to the transient stability of the system. Especially the mutual damping is cannot oversight, it can improve the transient stability of the system.更多还原