电网对称跌落故障时双馈风力发电机的改进控制策略研究

Research on improved control scheme for doubly fed induction generator in symmetrical drop fault of power grid

提出了一种基于有限集模型预测控制思想的扩展网侧变换器输入无功的控制方案,可有效地提升DFIG的低压跨失能力。DFIG系统通过网侧变流器直接与公共电网相连,当公共电网发生故障时,公共点电压不可避免地会出现跌落,严重时将会威胁DFIG的正常运行。当电网发生低电压故障时,应当采取相应的控制方案来抑制定子、转子过电流,避免变频器受到不利影响。以扩展网侧变换器的输入无功功率和维持网侧电流的稳定为控制目标,采用有限集模型预测控制来增强DFIG系统的故障穿越能力。仿真结果验证了DFIG在所提的有限集模型预测控制方案下优良的故障穿越能力。

Based on the finite-control-set model predictive control(FCS-MPC),an extending the input reactive power scheme of the grid side converter was presented to improve the capability of the fault ride through for the doubly fed induction generator(DFIG).The DFIG system is directly connected to the public power grid through the grid side converter.When the public power grid fails,the common point voltage will inevitably drop,which will threaten the normal operation of DFIG in serious cases.Thus,it is necessary to adopt the related control schemes to suppress the stator and rotor over-currents and avoid the adverse impact on the converter when the voltages of PCC drops.In this study,the control targets of the grid side converter are to generate reactive power as much as possible under PCC voltage faults and maintain the stable of the grid currents,which is realized by using the FCS-MPC control scheme.Finally,the good capability of the low voltage ride through for the DFIG with the proposed FCS-MPC control scheme was verified in the MATLAB/Simulink platform.