【摘要】 针对双馈风电机低电压穿越过程中存在的问题，在分析电压跌落时风机直流侧电压模型的基础上，提出了超级电容器经隔离型全桥DC/DC变换器并联在风机直流母线处。通过超级电容储能系统吸收电网低电压故障时在直流侧产生的不平衡功率，以此抑制直流母线过电压。为了满足电网低电压故障期间的无功需求，机侧变流器采用无功优先控制；网侧变流器则采用电压功率协调控制方法，两侧共同向电网输送无功。在故障切除后，将超级电容释放的功率引入到网侧变流器控制中作为前馈量，平衡超级电容的电能。最后仿真结果表明了该控制方案在电网发生故障时能有效抑制直流侧过电压，向电网提供无功功率帮助电网电压恢复；在故障切除后能够加快输出有功恢复，有效提升了双馈风电机组可靠性和经济性。更多还原

【Abstract】 In view of the problems existed in the low voltage ride through process of double-fed wind turbines,it is proposed that the super capacitor is connected in parallel to the DC bus via an isolated full-bridge DC/DC converter on the basis of analysis of the DC side voltage model of the wind turbine in the case of voltage drop.The DC bus over-voltage is suppressed by the unbalanced power which,in case the low voltage barrier at the grid side is absorbed by the super capacitor energy storage system,is generated at CD side. In order to meet the reactive power demand during the low voltage fault of grid,the reactive power priority control is adopted at the generator-side converter. While,the voltage and power coordinated control method is adopted for the converter at the grid side and the converters on both sides jointly provide reactive power to the grid. After fault clearance,the power released by the super capacitor is introduced to the converter control at the grid side as feed forward quantity so to balance the power of the super capacitor. Finally,simulation results show that the proposed control scheme can,in case of fault in the grid,effectively suppress the over-voltage at the DC side,provide reactive power to the grid and help recovery of grid voltage and can,after fault clearance,accelerate recovery of output active power as well as improve effectively the reliability and economy of DFIG wind turbine.更多还原