基于阻尼器的双馈风力发电系统扭振抑制策略

A novel torsional vibration damping method for a DFIG-based system

由风速扰动或网侧的电气扰动所引发的风机传动轴扭振现象会导致轴系机械零件疲劳过载,甚至损坏。提出一种对网侧电气小扰动引发机网扭振的抑制策略。该策略通过在转子侧逆变器功率控制环节引入阻尼器,当轴系发生扭振时,利用发电机转速波动信号产生阻尼功率,再附加到逆变器有功功率参考值上,使系统额外输出有功功率来增大系统阻尼,从而抑制轴系扭振。建立系统小信号稳定模型,分析扭振抑制原理,观察引入阻尼器后,系统主导扭振模态的特征根变化;并利用Bode图分析阻尼器对轴系扭振模态的抑制效果。最后,在Matlab/Simulink上进行仿真验证。结果表明,所提出的阻尼策略可以显著增大双馈风力发电系统的阻尼,增强对风力发电系统扭振尤其是低频振荡模态的抑制。

Torsional vibrations present in the drive train can produce large stresses on the components of the wind turbine. Those torsional vibrations can be excited by either turbulent winds or grid disturbances which are considered in this study. A damping system accomplished by the decoupled power control for rotor side converter equipped with a torsional damper is developed. During vibrations, the torsional damper extracts the ripple of the generator speed to produce an auxiliary active power reference, which enables the system to generate additional active power to damp the drive train vibrations. To illustrate the effectiveness of the torsional damper, eigenvalue analysis is conducted through small-signal stability model and Bode diagram of the closed loop system is plotted. Simulations are performed in Matlab/Simulink to evaluate the proposed damping method. Results confirm that the torsional damper can introduce an auxiliary damping to the wind turbine system and exhibit a good performance to damp both vibration frequencies of the drive train, particularly the low frequency mode. This work is supported by National Natural Science Foundation of China （No. 51277119）.