永磁直驱变速恒频风电系统并网逆变器研究

摘要

针对永磁直驱风电系统,采用全功率脉宽调制(PWM)逆变器实现变速恒频并网.并网逆变器采用基于电网电压定向的矢量控制策略.构建电压外环和电流内环,电压外环用于稳定直流电容电压,电流内环实现有功能量和无功能量的解耦输出.仿真和实验均表明该控制方法可实现系统单位功率因数运行,注入电网电流正弦度较高,并网电流总谐波畸变率(THD)低于5％,且系统具有较好的动、静态性能.%A direct-driven wind turbine with permanent magnet synchronous generator (PMSG) model connected with grid is established to study the issues on parallel,the grid voltage oriented control strategy is presented.The voltage feed-forward out loop and current decouple inner loop are introduced.PI controller is applied to both loops under d,q synchronous reference frame.And this control strategy is set up in Matlab/Simulink and hardware experiment,the results verify that the energy is decoupled to output.The grid-connected inverter can operate under unity power factor.The output current to grid can be with great characteristics of sine and total harmonic distortion(THD) is less than 5％.