电网电压跌落下无刷双馈发电机低电压穿越控制

Low Voltage Ride-Through Control of Brushless Doubly-Fed Generators Under Grid Voltage Drop

电网电压跌落的瞬间,风力发电机定子和转子产生冲击电压和冲击电流,对电网安全造成影响。为实现无刷双馈风力发电机低电压穿越,保证风电机组在电网电压跌落下不间断运行,对电网电压跌落下无刷双馈发电机定子电压和电流进行暂态分析,搭建了无刷双馈发电机在功率绕组静止坐标系下的数学模型,推导并分析了电网电压跌落瞬间其功率绕组磁链、控制绕组电压动态变化过程,并提出一种积分滑模直接功率控制与故障穿越控制相结合的控制策略,完成无刷双馈发电机低电压穿越控制。通过MATLAB/Simulink和半实物仿真试验平台进行验证,仿真和试验结果证明所推导功率绕组磁链和控制绕组电压动态变化过程的正确性及控制策略的有效性,该控制策略有效抑制了定子控制绕组侧电压和电流畸变,提高了无刷双馈发电机的低电压穿越性能。

When the grid voltage drops,the stator and rotor of the wind turbine generate impulse voltage and impulse current,which will affect the security of the grid.In order to realize the low voltage ride-through of the brushless doubly-fed wind turbine and ensure the uninterrupted operation of the wind turbine under the grid voltage drop,transient analysis of the stator voltage and current of the brushless doubly-fed generator under the grid voltage drop is conducted.A mathematical model of brushless doubly-fed generator in the static coordinate system of power winding is built,then the dynamic change process of its power winding flux linkage and control winding voltage at the moment of grid voltage drop is deduced and analyzed,moreover a control strategy combining integral sliding mode direct power control and fault ride through control is proposed,hence the low-voltage ride through control of brushless doubly-fed generator is completed.The control strategy combined with the fault ride-through control completes the low voltage ride-through control of the brushless doubly-fed generator.Through MATLAB/Simulink and the semi-physical simulation experiment platform,the simulation and experimental results prove the correctness of the deduced power winding flux and control winding voltage dynamic change process and the effectiveness of the control strategy.The control strategy effectively inhibits the voltage and current distortion of the stator control winding side and improves the low voltage crossing performance of the brushless doubly-fed generator.