并网故障下双馈感应风力发电系统的改进控制策略研究

IMPROVED CONTROL TECHNIQUES OF DFIG-BASED WIND ENERGY SYSTEMS UNDER DIFFERENT GRID FAULTS

介绍在并网故障下对双馈感应风力发电系统改进的控制策略研究。并网故障分为对称故障和不对称故障,在不对称故障情况下,当电网电压频率为60 Hz并且电机转速接近同步速时,在双馈感应风力发电机的转子中将会出现接近于120 Hz的转子电流主要谐波;在对称故障下,定子电压有一个瞬间跌落,从而会在转子中导致过电流、过电压、过转速的出现。该文中转子侧变频器(RSC)主要用于抑制在并网故障下转子中出现的谐波分量或过电流等现象;网侧变频器(GSC)则用于抑制变频器之间直流电容电压中出现的谐波,以维持直流电容电压恒定。所提出改进控制策略可更好地抑制并网故障,改善整个双馈感应风力发电系统的控制性能,并使用Matlab/Simulink仿真验证了控制效果。

An improved control technique for fault ride through of a doubly fed induction generator （DFIG）-based wind energy system was presented. Both unbalanced faults and balanced grid faults are considered. For unbalanced faults, a close to 120 Hz component will be presented in the rotor currents when the rotating speed is close to the synchronous d the frequency of the network voltage is 60 Hz. For balanced faults, the rotor currents will experience a side converters （RSC） control techniques presented in this paper is effective in mitigating the high frequency harmonic components and reducing the surge in the rotor currents. The grid side converters （GSC） control technique is also used to keep the voltage of DC-link constant and the new GSC control techniques proposed in this paper give the better dynamic performance compared to the previous paper. Simulations performed in Matlab/Simulink verify the effectiveness of the improved GSC control strategy.