直驱风电系统变流器建模和跌落特性仿真

为增强直驱型变速恒频风电系统的低电压穿越能力,采取了变流器直流侧增加卸荷负载以在故障时消耗掉直流侧多余的能量,使风电机组的正常运行基本不受电压跌落影响的应对措施。通过对发电机侧变流器、电网侧变流器和直流侧卸荷负载工作原理的详细分析,变流器采用背靠背双PWM结构,实现了变流器的整体建模。基于Matlab7.3/simulink6.5构建了变流器的仿真模型,对电网电压跌落时系统的跌落特性进行了变流器模型及其分析正确性的仿真验证,结果表明,采用直流侧卸荷负载可有效提高直驱系统的故障穿越能力,具有较快的动态响应速度。

Modeling on Converters of Direct-driven Wind Power System and Its Performance During Voltage Sags

To enhance the low voltage ride through(LVRT) capability of direct-driven variable-speed constant frequency(VSCF) wind power system,some countermeasures must be taken.By adding damp load at DC-side of the converter,redundant energy at DC-side during grid faults will be consumed,therefore the operating of wind turbine will not be influenced by grid voltage sags.The back-to-back dual PWM converter is used,and the principles of generator-side converter,grid-side converter and damp load are analyzed in detail,then the whole modeling of the converter is realized.The simulation model of the converter is developed based on the Matlab7.3/simulink6.5,and the performance during grid voltage sags is simulated,which demonstrates the validity of the model and analysis.The results show that direct-driven wind power system have good capability of fault ride through and fast dynamic respond speed by using damping load at DC-side.