【作者】 何亮；

【导师】 杨俊华；

【作者基本信息】 广东工业大学 ， 电力系统及其自动化， 2012， 硕士

【摘要】 风电机组装机容量的不断提高,促使国际风电技术的主要研究方向从电网正常条件下的运行转向电网故障条件下的穿越运行。风能属于不可控的能源,风电穿透率的提高会导致电网波动与闪变,电网不断对风电场接入提出更高的规范要求,风电技术领先的国家纷纷提出了故障穿越的标准。本文以主流的双馈异步风电机组和直驱型永磁同步风电机组为研究对象,围绕两种不同风电机组低电压穿越的相关问题进行研究,通过理论分析以及建模仿真,验证了研究的正确性。1、分析了两种主流变速恒频风电机组的结构,建立风力发电系统空气动力模型及传动系统模型。2、针对交流励磁双馈发电机组(DFIG),通过坐标变换建立了两相同步旋转坐标系下的DFIG发电机及网侧、转子侧PWM变换器的完整数学模型。提出了基于电网电压定向的网侧PWM变换器电压、电流双闭环控制策略；针对转子侧PWM变换器,计及定子电压和励磁电流,建立了两相同步旋转坐标系下的DFIG精确控制模型,提出了基于定子电压定向的改进矢量控制方案。通过仿真,验证了所建模型的有效性,为分析双馈发电机组的低电压穿越能力奠定了基础。3、针对直驱型永磁同步发电机组,首先建立了永磁同步发电机和PWM变换器的模型,分析了PWM变换器的能量传输,提出了采用电网电压定向的网侧变换器矢量控制策略,以及采用转子磁场定向的机侧矢量控制策略。仿真验证了所选方案的正确性,为分析永磁同步发电机组低电压穿越能力提供了仿真平台。4、分别分析了两种风电机组在严重对称电压跌落时的控制方案。针对双馈风电机组分析了Crowbar投切时间对系统的影响,以及转子Crowbar所串电阻的大小电网恢复的影响。针对水磁同同步发电机组,提出了直驱型永磁风力发电系统低电压穿越的控制逻辑,采用储能Crowbar,故障时无功控制策略实现了永磁同步风力发电系统的低电压穿越。更多还原

【Abstract】 As the increased penetration of wind power generations in power system, modern grid codes concerning grid-connected wind turbines are developed. As a result, the wind turbine under normal grid conditions is well understood and applied, the fault ride-through operation and control of the wind power system when grid fault condition has been the main subject of much recent research and development worldwide. Because of the uncontrolled wind power and the grid system fault, countries have advantage over wind power generation have already come up with different standards of fault ride-through. This dissertation intends to study the control of DFIG and PMSG wind turbine in low voltage ride through technology. Verify the correctness of the study by theoretical analysis and the simulation model.1. Introduce the construction of two mainstream VSCF wind turbine, build up the aerodynamic model of the wind power system and the driveline components.2. The precise mathematical model of DFIG’s grid-side converter and rotor-side converter are created. Based on the model, the dissertation presents an integrated system model with network, DFIG, grid-side converter and rotor-side converter included in the two-phase synchronous reference frame. Thereafter, a classical vector control scheme based on grid/stator voltage orientation and composed of dual closed-loops, viz., DC-link voltage control and AC current control loops, for DFIG’s grid-side converter is introduced. While for rotor-side converter a precise control model taking the stator voltage variation transients into account is constructed in the synchronous reference frame, and improved vector control scheme is suggested based on stator voltage orientation. Simulated analysis verifies the correctness and effectiveness of the proposed DFIG’s control model and the system’s new vector control scheme under relatively grid voltage sag.3. The mathematical model of PWM converter is studied, and the part of the DC of Dual-PWM is described through analyzing the power transformation theory. The simulation models of the controller of grid-side converter which uses voltage-oreinted vector control strategy and the controller of motor-side converter which uses the rotor flux-oriented vector control strategy are built, and the simulation results show that the model and the control strategy are correct, which provides simulation platform support for the low voltage ride through.4. The dissertation studies control strategies and protection schemes for DFIG wind generation systems under serious grid voltage dip conditions. The timing of rotor crowbar’s switching on and off is optimized. The impact of value of resistor series-connected to rotor crowbar on faulted network recovery is analyzed. On the basis, a fault ride-through operation scheme composed of a series-connected resistor rotor crowbar and an improved grid-side converter control strategy is proposed. In PMSG, the study puts forward a set of control logic for the based low voltage ride through. In the directly-driven permanent magnet wind power system simulation platform, the low voltage ride through of directly-driven PM wind generation system is achieved by using the power storage crowbar and reactive power control strategy during the breakdown time.更多还原